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x86/mm: Fix use of uninitialized buffer in sme_enable()

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cmdline_find_option() may fail before doing any initialization of
the buffer array. This may lead to unpredictable results when the same
buffer is used later in calls to strncmp() function.  Fix the issue by
returning early if cmdline_find_option() returns an error.

Found by Linux Verification Center (linuxtesting.org) with static
analysis tool SVACE.

Fixes: aca20d5462 ("x86/mm: Add support to make use of Secure Memory Encryption")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: <stable@kernel.org>
Link: https://lore.kernel.org/r/20230306160656.14844-1-n.zhandarovich@fintech.ru
This commit is contained in:
Nikita Zhandarovich 2023-03-06 08:06:56 -08:00 committed by Borislav Petkov (AMD)
parent 0424a7dfe9
commit cbebd68f59
1 changed files with 2 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

3
arch/x86/mm/mem_encrypt_identity.c
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@ -600,7 +600,8 @@ void __init sme_enable(struct boot_params *bp)
cmdline_ptr = (const char *)((u64)bp->hdr.cmd_line_ptr |
((u64)bp->ext_cmd_line_ptr << 32));
cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer));
if (cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer)) < 0)
return;
if (!strncmp(buffer, cmdline_on, sizeof(buffer)))
sme_me_mask = me_mask;