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x86/RAS/mce_amd_inj: Fix signed wrap around when decrementing index 'i' 

Change predecrement compare to post decrement compare to avoid an
unsigned integer wrap-around comparisomn when decrementing in the while
loop.

For example, if the debugfs_create_file() fails when 'i' is zero, the
current situation will predecrement 'i' in the while loop, wrapping 'i' to
the maximum signed integer and cause multiple out of bounds reads on
dfs_fls[i].d as the loop interates to zero.

Also, as Borislav Petkov suggested, return -ENODEV rather than -ENOMEM
on the error condition.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yazen Ghannam <Yazen.Ghannam@amd.com>
Link: http://lkml.kernel.org/r/20160926083152.30848-2-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
hifive-unleashed-5.1
Colin Ian King 2016-09-26 10:31:51 +02:00 committed by Ingo Molnar
parent 6fae257f0b
commit 8b44f00f8c
1 changed files with 2 additions and 2 deletions
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4
arch/x86/ras/mce_amd_inj.c
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@ -464,13 +464,13 @@ static int __init init_mce_inject(void)
return 0;
err_dfs_add:
while (--i >= 0)
while (i-- > 0)
debugfs_remove(dfs_fls[i].d);
debugfs_remove(dfs_inj);
dfs_inj = NULL;
return -ENOMEM;
return -ENODEV;
}
static void __exit exit_mce_inject(void)