Fix a race condition in LKL's clone support. #4
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If LKL shut down before a cloned thread issued its first system call, the cloned thread would have the wrong host thread pointer and so the host thread would be freed twice.
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This should fix lsds/sgx-lkl#627 |
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commit fc846e9 upstream. The `INSN_CONFIG` comedi instruction with sub-instruction code `INSN_CONFIG_DIGITAL_TRIG` includes a base channel in `data[3]`. This is used as a right shift amount for other bitmask values without being checked. Shift amounts greater than or equal to 32 will result in undefined behavior. Add code to deal with this, adjusting the checks for invalid channels so that enabled channel bits that would have been lost by shifting are also checked for validity. Only channels 0 to 15 are valid. Fixes: a8c66b6 ("staging: comedi: addi_apci_1500: rewrite the subdevice support functions") Cc: <stable@vger.kernel.org> #4.0+: ef75e14: staging: comedi: verify array index is correct before using it Cc: <stable@vger.kernel.org> #4.0+ Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Link: https://lore.kernel.org/r/20200717145257.112660-5-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 254503a upstream. The drm/omap driver was fixed to correct an issue where using a divider of 32 breaks the DSS despite the TRM stating 32 is a valid number. Through experimentation, it appears that 31 works, and it is consistent with the value used by the drm/omap driver. This patch fixes the divider for fbdev driver instead of the drm. Fixes: f76ee89 ("omapfb: copy omapdss & displays for omapfb") Cc: <stable@vger.kernel.org> #4.5+ Signed-off-by: Adam Ford <aford173@gmail.com> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com> Cc: Dave Airlie <airlied@gmail.com> Cc: Rob Clark <robdclark@gmail.com> [b.zolnierkie: mark patch as applicable to stable 4.5+ (was 4.9+)] Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200630182636.439015-1-aford173@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit e24c644 ] I compiled with AddressSanitizer and I had these memory leaks while I was using the tep_parse_format function: Direct leak of 28 byte(s) in 4 object(s) allocated from: #0 0x7fb07db49ffe in __interceptor_realloc (/lib/x86_64-linux-gnu/libasan.so.5+0x10dffe) #1 0x7fb07a724228 in extend_token /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:985 #2 0x7fb07a724c21 in __read_token /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:1140 #3 0x7fb07a724f78 in read_token /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:1206 #4 0x7fb07a725191 in __read_expect_type /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:1291 #5 0x7fb07a7251df in read_expect_type /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:1299 #6 0x7fb07a72e6c8 in process_dynamic_array_len /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:2849 #7 0x7fb07a7304b8 in process_function /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:3161 #8 0x7fb07a730900 in process_arg_token /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:3207 #9 0x7fb07a727c0b in process_arg /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:1786 #10 0x7fb07a731080 in event_read_print_args /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:3285 lkl#11 0x7fb07a731722 in event_read_print /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:3369 lkl#12 0x7fb07a740054 in __tep_parse_format /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:6335 lkl#13 0x7fb07a74047a in __parse_event /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:6389 lkl#14 0x7fb07a740536 in tep_parse_format /home/pduplessis/repo/linux/tools/lib/traceevent/event-parse.c:6431 lkl#15 0x7fb07a785acf in parse_event ../../../src/fs-src/fs.c:251 lkl#16 0x7fb07a785ccd in parse_systems ../../../src/fs-src/fs.c:284 lkl#17 0x7fb07a786fb3 in read_metadata ../../../src/fs-src/fs.c:593 lkl#18 0x7fb07a78760e in ftrace_fs_source_init ../../../src/fs-src/fs.c:727 lkl#19 0x7fb07d90c19c in add_component_with_init_method_data ../../../../src/lib/graph/graph.c:1048 lkl#20 0x7fb07d90c87b in add_source_component_with_initialize_method_data ../../../../src/lib/graph/graph.c:1127 lkl#21 0x7fb07d90c92a in bt_graph_add_source_component ../../../../src/lib/graph/graph.c:1152 lkl#22 0x55db11aa632e in cmd_run_ctx_create_components_from_config_components ../../../src/cli/babeltrace2.c:2252 lkl#23 0x55db11aa6fda in cmd_run_ctx_create_components ../../../src/cli/babeltrace2.c:2347 lkl#24 0x55db11aa780c in cmd_run ../../../src/cli/babeltrace2.c:2461 lkl#25 0x55db11aa8a7d in main ../../../src/cli/babeltrace2.c:2673 lkl#26 0x7fb07d5460b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2) The token variable in the process_dynamic_array_len function is allocated in the read_expect_type function, but is not freed before calling the read_token function. Free the token variable before calling read_token in order to plug the leak. Signed-off-by: Philippe Duplessis-Guindon <pduplessis@efficios.com> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Link: https://lore.kernel.org/linux-trace-devel/20200730150236.5392-1-pduplessis@efficios.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit ab0db04 ] When running with -o enospc_debug you can get the following splat if one of the dump_space_info's trip ====================================================== WARNING: possible circular locking dependency detected 5.8.0-rc5+ lkl#20 Tainted: G OE ------------------------------------------------------ dd/563090 is trying to acquire lock: ffff9e7dbf4f1e18 (&ctl->tree_lock){+.+.}-{2:2}, at: btrfs_dump_free_space+0x2b/0xa0 [btrfs] but task is already holding lock: ffff9e7e2284d428 (&cache->lock){+.+.}-{2:2}, at: btrfs_dump_space_info+0xaa/0x120 [btrfs] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&cache->lock){+.+.}-{2:2}: _raw_spin_lock+0x25/0x30 btrfs_add_reserved_bytes+0x3c/0x3c0 [btrfs] find_free_extent+0x7ef/0x13b0 [btrfs] btrfs_reserve_extent+0x9b/0x180 [btrfs] btrfs_alloc_tree_block+0xc1/0x340 [btrfs] alloc_tree_block_no_bg_flush+0x4a/0x60 [btrfs] __btrfs_cow_block+0x122/0x530 [btrfs] btrfs_cow_block+0x106/0x210 [btrfs] commit_cowonly_roots+0x55/0x300 [btrfs] btrfs_commit_transaction+0x4ed/0xac0 [btrfs] sync_filesystem+0x74/0x90 generic_shutdown_super+0x22/0x100 kill_anon_super+0x14/0x30 btrfs_kill_super+0x12/0x20 [btrfs] deactivate_locked_super+0x36/0x70 cleanup_mnt+0x104/0x160 task_work_run+0x5f/0x90 __prepare_exit_to_usermode+0x1bd/0x1c0 do_syscall_64+0x5e/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #2 (&space_info->lock){+.+.}-{2:2}: _raw_spin_lock+0x25/0x30 btrfs_block_rsv_release+0x1a6/0x3f0 [btrfs] btrfs_inode_rsv_release+0x4f/0x170 [btrfs] btrfs_clear_delalloc_extent+0x155/0x480 [btrfs] clear_state_bit+0x81/0x1a0 [btrfs] __clear_extent_bit+0x25c/0x5d0 [btrfs] clear_extent_bit+0x15/0x20 [btrfs] btrfs_invalidatepage+0x2b7/0x3c0 [btrfs] truncate_cleanup_page+0x47/0xe0 truncate_inode_pages_range+0x238/0x840 truncate_pagecache+0x44/0x60 btrfs_setattr+0x202/0x5e0 [btrfs] notify_change+0x33b/0x490 do_truncate+0x76/0xd0 path_openat+0x687/0xa10 do_filp_open+0x91/0x100 do_sys_openat2+0x215/0x2d0 do_sys_open+0x44/0x80 do_syscall_64+0x52/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #1 (&tree->lock#2){+.+.}-{2:2}: _raw_spin_lock+0x25/0x30 find_first_extent_bit+0x32/0x150 [btrfs] write_pinned_extent_entries.isra.0+0xc5/0x100 [btrfs] __btrfs_write_out_cache+0x172/0x480 [btrfs] btrfs_write_out_cache+0x7a/0xf0 [btrfs] btrfs_write_dirty_block_groups+0x286/0x3b0 [btrfs] commit_cowonly_roots+0x245/0x300 [btrfs] btrfs_commit_transaction+0x4ed/0xac0 [btrfs] close_ctree+0xf9/0x2f5 [btrfs] generic_shutdown_super+0x6c/0x100 kill_anon_super+0x14/0x30 btrfs_kill_super+0x12/0x20 [btrfs] deactivate_locked_super+0x36/0x70 cleanup_mnt+0x104/0x160 task_work_run+0x5f/0x90 __prepare_exit_to_usermode+0x1bd/0x1c0 do_syscall_64+0x5e/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #0 (&ctl->tree_lock){+.+.}-{2:2}: __lock_acquire+0x1240/0x2460 lock_acquire+0xab/0x360 _raw_spin_lock+0x25/0x30 btrfs_dump_free_space+0x2b/0xa0 [btrfs] btrfs_dump_space_info+0xf4/0x120 [btrfs] btrfs_reserve_extent+0x176/0x180 [btrfs] __btrfs_prealloc_file_range+0x145/0x550 [btrfs] cache_save_setup+0x28d/0x3b0 [btrfs] btrfs_start_dirty_block_groups+0x1fc/0x4f0 [btrfs] btrfs_commit_transaction+0xcc/0xac0 [btrfs] btrfs_alloc_data_chunk_ondemand+0x162/0x4c0 [btrfs] btrfs_check_data_free_space+0x4c/0xa0 [btrfs] btrfs_buffered_write.isra.0+0x19b/0x740 [btrfs] btrfs_file_write_iter+0x3cf/0x610 [btrfs] new_sync_write+0x11e/0x1b0 vfs_write+0x1c9/0x200 ksys_write+0x68/0xe0 do_syscall_64+0x52/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 other info that might help us debug this: Chain exists of: &ctl->tree_lock --> &space_info->lock --> &cache->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&cache->lock); lock(&space_info->lock); lock(&cache->lock); lock(&ctl->tree_lock); *** DEADLOCK *** 6 locks held by dd/563090: #0: ffff9e7e21d18448 (sb_writers#14){.+.+}-{0:0}, at: vfs_write+0x195/0x200 #1: ffff9e7dd0410ed8 (&sb->s_type->i_mutex_key#19){++++}-{3:3}, at: btrfs_file_write_iter+0x86/0x610 [btrfs] #2: ffff9e7e21d18638 (sb_internal#2){.+.+}-{0:0}, at: start_transaction+0x40b/0x5b0 [btrfs] #3: ffff9e7e1f05d688 (&cur_trans->cache_write_mutex){+.+.}-{3:3}, at: btrfs_start_dirty_block_groups+0x158/0x4f0 [btrfs] #4: ffff9e7e2284ddb8 (&space_info->groups_sem){++++}-{3:3}, at: btrfs_dump_space_info+0x69/0x120 [btrfs] #5: ffff9e7e2284d428 (&cache->lock){+.+.}-{2:2}, at: btrfs_dump_space_info+0xaa/0x120 [btrfs] stack backtrace: CPU: 3 PID: 563090 Comm: dd Tainted: G OE 5.8.0-rc5+ lkl#20 Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./890FX Deluxe5, BIOS P1.40 05/03/2011 Call Trace: dump_stack+0x96/0xd0 check_noncircular+0x162/0x180 __lock_acquire+0x1240/0x2460 ? wake_up_klogd.part.0+0x30/0x40 lock_acquire+0xab/0x360 ? btrfs_dump_free_space+0x2b/0xa0 [btrfs] _raw_spin_lock+0x25/0x30 ? btrfs_dump_free_space+0x2b/0xa0 [btrfs] btrfs_dump_free_space+0x2b/0xa0 [btrfs] btrfs_dump_space_info+0xf4/0x120 [btrfs] btrfs_reserve_extent+0x176/0x180 [btrfs] __btrfs_prealloc_file_range+0x145/0x550 [btrfs] ? btrfs_qgroup_reserve_data+0x1d/0x60 [btrfs] cache_save_setup+0x28d/0x3b0 [btrfs] btrfs_start_dirty_block_groups+0x1fc/0x4f0 [btrfs] btrfs_commit_transaction+0xcc/0xac0 [btrfs] ? start_transaction+0xe0/0x5b0 [btrfs] btrfs_alloc_data_chunk_ondemand+0x162/0x4c0 [btrfs] btrfs_check_data_free_space+0x4c/0xa0 [btrfs] btrfs_buffered_write.isra.0+0x19b/0x740 [btrfs] ? ktime_get_coarse_real_ts64+0xa8/0xd0 ? trace_hardirqs_on+0x1c/0xe0 btrfs_file_write_iter+0x3cf/0x610 [btrfs] new_sync_write+0x11e/0x1b0 vfs_write+0x1c9/0x200 ksys_write+0x68/0xe0 do_syscall_64+0x52/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 This is because we're holding the block_group->lock while trying to dump the free space cache. However we don't need this lock, we just need it to read the values for the printk, so move the free space cache dumping outside of the block group lock. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit 9f4aa52 upstream. During initialization of the DASD DIAG driver a request is issued that has a bio structure that resides on the stack. With virtually mapped kernel stacks this bio address might be in virtual storage which is unsuitable for usage with the diag250 call. In this case the device can not be set online using the DIAG discipline and fails with -EOPNOTSUP. In the system journal the following error message is presented: dasd: X.X.XXXX Setting the DASD online with discipline DIAG failed with rc=-95 Fix by allocating the bio structure instead of having it on the stack. Fixes: ce3dc44 ("s390: add support for virtually mapped kernel stacks") Signed-off-by: Stefan Haberland <sth@linux.ibm.com> Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com> Cc: stable@vger.kernel.org #4.20 Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 18c850f upstream. There's long existed a lockdep splat because we open our bdev's under the ->device_list_mutex at mount time, which acquires the bd_mutex. Usually this goes unnoticed, but if you do loopback devices at all suddenly the bd_mutex comes with a whole host of other dependencies, which results in the splat when you mount a btrfs file system. ====================================================== WARNING: possible circular locking dependency detected 5.8.0-0.rc3.1.fc33.x86_64+debug #1 Not tainted ------------------------------------------------------ systemd-journal/509 is trying to acquire lock: ffff970831f84db0 (&fs_info->reloc_mutex){+.+.}-{3:3}, at: btrfs_record_root_in_trans+0x44/0x70 [btrfs] but task is already holding lock: ffff97083144d598 (sb_pagefaults){.+.+}-{0:0}, at: btrfs_page_mkwrite+0x59/0x560 [btrfs] which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #6 (sb_pagefaults){.+.+}-{0:0}: __sb_start_write+0x13e/0x220 btrfs_page_mkwrite+0x59/0x560 [btrfs] do_page_mkwrite+0x4f/0x130 do_wp_page+0x3b0/0x4f0 handle_mm_fault+0xf47/0x1850 do_user_addr_fault+0x1fc/0x4b0 exc_page_fault+0x88/0x300 asm_exc_page_fault+0x1e/0x30 -> #5 (&mm->mmap_lock#2){++++}-{3:3}: __might_fault+0x60/0x80 _copy_from_user+0x20/0xb0 get_sg_io_hdr+0x9a/0xb0 scsi_cmd_ioctl+0x1ea/0x2f0 cdrom_ioctl+0x3c/0x12b4 sr_block_ioctl+0xa4/0xd0 block_ioctl+0x3f/0x50 ksys_ioctl+0x82/0xc0 __x64_sys_ioctl+0x16/0x20 do_syscall_64+0x52/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #4 (&cd->lock){+.+.}-{3:3}: __mutex_lock+0x7b/0x820 sr_block_open+0xa2/0x180 __blkdev_get+0xdd/0x550 blkdev_get+0x38/0x150 do_dentry_open+0x16b/0x3e0 path_openat+0x3c9/0xa00 do_filp_open+0x75/0x100 do_sys_openat2+0x8a/0x140 __x64_sys_openat+0x46/0x70 do_syscall_64+0x52/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #3 (&bdev->bd_mutex){+.+.}-{3:3}: __mutex_lock+0x7b/0x820 __blkdev_get+0x6a/0x550 blkdev_get+0x85/0x150 blkdev_get_by_path+0x2c/0x70 btrfs_get_bdev_and_sb+0x1b/0xb0 [btrfs] open_fs_devices+0x88/0x240 [btrfs] btrfs_open_devices+0x92/0xa0 [btrfs] btrfs_mount_root+0x250/0x490 [btrfs] legacy_get_tree+0x30/0x50 vfs_get_tree+0x28/0xc0 vfs_kern_mount.part.0+0x71/0xb0 btrfs_mount+0x119/0x380 [btrfs] legacy_get_tree+0x30/0x50 vfs_get_tree+0x28/0xc0 do_mount+0x8c6/0xca0 __x64_sys_mount+0x8e/0xd0 do_syscall_64+0x52/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #2 (&fs_devs->device_list_mutex){+.+.}-{3:3}: __mutex_lock+0x7b/0x820 btrfs_run_dev_stats+0x36/0x420 [btrfs] commit_cowonly_roots+0x91/0x2d0 [btrfs] btrfs_commit_transaction+0x4e6/0x9f0 [btrfs] btrfs_sync_file+0x38a/0x480 [btrfs] __x64_sys_fdatasync+0x47/0x80 do_syscall_64+0x52/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #1 (&fs_info->tree_log_mutex){+.+.}-{3:3}: __mutex_lock+0x7b/0x820 btrfs_commit_transaction+0x48e/0x9f0 [btrfs] btrfs_sync_file+0x38a/0x480 [btrfs] __x64_sys_fdatasync+0x47/0x80 do_syscall_64+0x52/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 -> #0 (&fs_info->reloc_mutex){+.+.}-{3:3}: __lock_acquire+0x1241/0x20c0 lock_acquire+0xb0/0x400 __mutex_lock+0x7b/0x820 btrfs_record_root_in_trans+0x44/0x70 [btrfs] start_transaction+0xd2/0x500 [btrfs] btrfs_dirty_inode+0x44/0xd0 [btrfs] file_update_time+0xc6/0x120 btrfs_page_mkwrite+0xda/0x560 [btrfs] do_page_mkwrite+0x4f/0x130 do_wp_page+0x3b0/0x4f0 handle_mm_fault+0xf47/0x1850 do_user_addr_fault+0x1fc/0x4b0 exc_page_fault+0x88/0x300 asm_exc_page_fault+0x1e/0x30 other info that might help us debug this: Chain exists of: &fs_info->reloc_mutex --> &mm->mmap_lock#2 --> sb_pagefaults Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sb_pagefaults); lock(&mm->mmap_lock#2); lock(sb_pagefaults); lock(&fs_info->reloc_mutex); *** DEADLOCK *** 3 locks held by systemd-journal/509: #0: ffff97083bdec8b8 (&mm->mmap_lock#2){++++}-{3:3}, at: do_user_addr_fault+0x12e/0x4b0 #1: ffff97083144d598 (sb_pagefaults){.+.+}-{0:0}, at: btrfs_page_mkwrite+0x59/0x560 [btrfs] #2: ffff97083144d6a8 (sb_internal){.+.+}-{0:0}, at: start_transaction+0x3f8/0x500 [btrfs] stack backtrace: CPU: 0 PID: 509 Comm: systemd-journal Not tainted 5.8.0-0.rc3.1.fc33.x86_64+debug #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Call Trace: dump_stack+0x92/0xc8 check_noncircular+0x134/0x150 __lock_acquire+0x1241/0x20c0 lock_acquire+0xb0/0x400 ? btrfs_record_root_in_trans+0x44/0x70 [btrfs] ? lock_acquire+0xb0/0x400 ? btrfs_record_root_in_trans+0x44/0x70 [btrfs] __mutex_lock+0x7b/0x820 ? btrfs_record_root_in_trans+0x44/0x70 [btrfs] ? kvm_sched_clock_read+0x14/0x30 ? sched_clock+0x5/0x10 ? sched_clock_cpu+0xc/0xb0 btrfs_record_root_in_trans+0x44/0x70 [btrfs] start_transaction+0xd2/0x500 [btrfs] btrfs_dirty_inode+0x44/0xd0 [btrfs] file_update_time+0xc6/0x120 btrfs_page_mkwrite+0xda/0x560 [btrfs] ? sched_clock+0x5/0x10 do_page_mkwrite+0x4f/0x130 do_wp_page+0x3b0/0x4f0 handle_mm_fault+0xf47/0x1850 do_user_addr_fault+0x1fc/0x4b0 exc_page_fault+0x88/0x300 ? asm_exc_page_fault+0x8/0x30 asm_exc_page_fault+0x1e/0x30 RIP: 0033:0x7fa3972fdbfe Code: Bad RIP value. Fix this by not holding the ->device_list_mutex at this point. The device_list_mutex exists to protect us from modifying the device list while the file system is running. However it can also be modified by doing a scan on a device. But this action is specifically protected by the uuid_mutex, which we are holding here. We cannot race with opening at this point because we have the ->s_mount lock held during the mount. Not having the ->device_list_mutex here is perfectly safe as we're not going to change the devices at this point. CC: stable@vger.kernel.org # 4.19+ Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> [ add some comments ] Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Sep 7, 2020
commit 2d9a2c5 upstream. Before v4.15 commit 75492a5 ("s390/scsi: Convert timers to use timer_setup()"), we intentionally only passed zfcp_adapter as context argument to zfcp_fsf_request_timeout_handler(). Since we only trigger adapter recovery, it was unnecessary to sync against races between timeout and (late) completion. Likewise, we only passed zfcp_erp_action as context argument to zfcp_erp_timeout_handler(). Since we only wakeup an ERP action, it was unnecessary to sync against races between timeout and (late) completion. Meanwhile the timeout handlers get timer_list as context argument and do a timer-specific container-of to zfcp_fsf_req which can have been freed. Fix it by making sure that any request timeout handlers, that might just have started before del_timer(), are completed by using del_timer_sync() instead. This ensures the request free happens afterwards. Space time diagram of potential use-after-free: Basic idea is to have 2 or more pending requests whose timeouts run out at almost the same time. req 1 timeout ERP thread req 2 timeout ---------------- ---------------- --------------------------------------- zfcp_fsf_request_timeout_handler fsf_req = from_timer(fsf_req, t, timer) adapter = fsf_req->adapter zfcp_qdio_siosl(adapter) zfcp_erp_adapter_reopen(adapter,...) zfcp_erp_strategy ... zfcp_fsf_req_dismiss_all list_for_each_entry_safe zfcp_fsf_req_complete 1 del_timer 1 zfcp_fsf_req_free 1 zfcp_fsf_req_complete 2 zfcp_fsf_request_timeout_handler del_timer 2 fsf_req = from_timer(fsf_req, t, timer) zfcp_fsf_req_free 2 adapter = fsf_req->adapter ^^^^^^^ already freed Link: https://lore.kernel.org/r/20200813152856.50088-1-maier@linux.ibm.com Fixes: 75492a5 ("s390/scsi: Convert timers to use timer_setup()") Cc: <stable@vger.kernel.org> #4.15+ Suggested-by: Julian Wiedmann <jwi@linux.ibm.com> Reviewed-by: Julian Wiedmann <jwi@linux.ibm.com> Signed-off-by: Steffen Maier <maier@linux.ibm.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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If LKL shut down before a cloned thread issued its first system call,
the cloned thread would have the wrong host thread pointer and so the
host thread would be freed twice.