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aacraid: prevent invalid pointer dereference

It appears that driver runs into a problem here if fibsize is too small
because we allocate user_srbcmd with fibsize size only but later we
access it until user_srbcmd->sg.count to copy it over to srbcmd.

It is not correct to test (fibsize < sizeof(*user_srbcmd)) because this
structure already includes one sg element and this is not needed for
commands without data.  So, we would recommend to add the following
(instead of test for fibsize == 0).

Signed-off-by: Mahesh Rajashekhara <Mahesh.Rajashekhara@pmcs.com>
Reported-by: Nico Golde <nico@ngolde.de>
Reported-by: Fabian Yamaguchi <fabs@goesec.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1 parent 1ee2dcc commit b4789b8e6be3151a955ade74872822f30e8cd914 Mahesh Rajashekhara committed with Oct 31, 2013
Showing with 2 additions and 1 deletion.
  1. +2 −1 drivers/scsi/aacraid/commctrl.c
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3 drivers/scsi/aacraid/commctrl.c
@@ -511,7 +511,8 @@ static int aac_send_raw_srb(struct aac_dev* dev, void __user * arg)
goto cleanup;
}
- if (fibsize > (dev->max_fib_size - sizeof(struct aac_fibhdr))) {
+ if ((fibsize < (sizeof(struct user_aac_srb) - sizeof(struct user_sgentry))) ||
+ (fibsize > (dev->max_fib_size - sizeof(struct aac_fibhdr)))) {
rcode = -EINVAL;
goto cleanup;
}

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