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net:stmmac: fix broken stmmac_pltfr_remove.
This patch fixes stmmac_pltfr_remove function, which is broken because, it is accessing plat variable via freed memory priv pointer which gets freed by free_netdev called from stmmac_dvr_remove. In short this patch caches the plat pointer in local variable before calling stmmac_dvr_remove to prevent code accessing freed memory. Without this patch any attempt to remove the stmmac device will fail as below: Unregistering eth 0 ... Unable to handle kernel paging request at virtual address 6b6b6bab pgd = de5dc000 [6b6b6bab] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT SMP Modules linked in: cdev(O+) CPU: 0 Tainted: G O (3.3.1_stm24_0210-b2000+ #25) PC is at stmmac_pltfr_remove+0x2c/0xa0 LR is at stmmac_pltfr_remove+0x28/0xa0 pc : [<c01b8908>] lr : [<c01b8904>] psr: 60000013 sp : def6be78 ip : de6c5a00 fp : 00000000 r10: 00000028 r9 : c082d81d r8 : 00000001 r7 : de65a600 r6 : df81b240 r5 : c0413fd8 r4 : 00000000 r3 : 6b6b6b6b r2 : def6be6c r1 : c0355e2b r0 : 00000020 Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment user Control: 10c53c7d Table: 5e5dc04a DAC: 00000015 Process insmod (pid: 738, stack limit = 0xdef6a2f0) Stack: (0xdef6be78 to 0xdef6c000) be60: c0413fe0 c0403658 be80: c0400bb0 c019270c c01926f8 c0191478 00000000 c0414014 c0413fe0 c01914d8 bea0: 00000000 c0413fe0 df8045d0 c019109c c0413fe0 c0400bf0 c0413fd8 c018f04c bec0: 00000000 bf000000 c0413fd8 c01929a0 c0413fd8 bf000000 00000000 c0192bfc bee0: bf00009c bf000014 def6a000 c000859c 00000000 00000001 bf00009c bf00009c bf00: 00000001 bf00009c 00000001 bf0000e4 de65a600 00000001 c082d81d c0058cd0 bf20: bf0000a8 c004fbd8 c0056414 c082d815 c02aea20 bf0001f0 00b0b008 e0846208 bf40: c03ec8a0 e0846000 0000db0d e0850604 e08504de e0853a24 00000204 000002d4 bf60: 00000000 00000000 0000001c 0000001d 00000009 00000000 00000006 00000000 bf80: 00000003 f63d4e2e 0000db0d bef02ed8 00000080 c000d2e8 def6a000 00000000 bfa0: 00000000 c000d140 f63d4e2e 0000db0d 00b0b018 0000db0d 00b0b008 b6f4f298 bfc0: f63d4e2e 0000db0d bef02ed8 00000080 00000003 00000000 00010000 00000000 bfe0: 00b0b008 bef02c64 00008d20 b6ef3784 60000010 00b0b018 5a5a5a5a 5a5a5a5a [<c01b8908>] (stmmac_pltfr_remove+0x2c/0xa0) from [<c019270c>] (platform_drv_remove+0x14/0x18) [<c019270c>] (platform_drv_remove+0x14/0x18) from [<c0191478>] (__device_release_driver+0x64/0xa4) [<c0191478>] (__device_release_driver+0x64/0xa4) from [<c01914d8>] (device_release_driver+0x20/0x2c) [<c01914d8>] (device_release_driver+0x20/0x2c) from [<c019109c>] (bus_remove_device+0xcc/0xdc) [<c019109c>] (bus_remove_device+0xcc/0xdc) from [<c018f04c>] (device_del+0x104/0x160) [<c018f04c>] (device_del+0x104/0x160) from [<c01929a0>] (platform_device_del+0x18/0x58) [<c01929a0>] (platform_device_del+0x18/0x58) from [<c0192bfc>] (platform_device_unregister+0xc/0x18) [<c0192bfc>] (platform_device_unregister+0xc/0x18) from [<bf000014>] (r_init+0x14/0x2c [cdev]) [<bf000014>] (r_init+0x14/0x2c [cdev]) from [<c000859c>] (do_one_initcall+0x90/0x160) [<c000859c>] (do_one_initcall+0x90/0x160) from [<c0058cd0>] (sys_init_module+0x15c4/0x1794) [<c0058cd0>] (sys_init_module+0x15c4/0x1794) from [<c000d140>] (ret_fast_syscall+0x0/0x30) Code: e1a04000 e59f0070 eb039b65 e59636e4 (e5933040) Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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