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x86/microcode/AMD: Subtract SECTION_HDR_SIZE from file leftover length 

verify_patch_size() verifies whether the remaining size of the microcode
container file is large enough to contain a patch of the indicated size.

However, the section header length is not included in this indicated
size but it is present in the leftover file length so it should be
subtracted from the leftover file length before passing this value to
verify_patch_size().

 [ bp: Split comment. ]

Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/6df43f4f6a28186a13a66e8d7e61143c5e1a2324.1529424596.git.mail@maciej.szmigiero.name
This commit is contained in:
Maciej S. Szmigiero 2018-06-19 20:47:31 +02:00 committed by Borislav Petkov
parent 9ff01193a2
commit 479229d160
1 changed files with 12 additions and 3 deletions
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15
arch/x86/kernel/cpu/microcode/amd.c
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@ -461,8 +461,12 @@ static int collect_cpu_info_amd(int cpu, struct cpu_signature *csig)
return 0;
}
static unsigned int verify_patch_size(u8 family, u32 patch_size,
unsigned int size)
/*
* Check whether the passed remaining file @size is large enough to contain a
* patch of the indicated @patch_size (and also whether this size does not
* exceed the per-family maximum).
*/
static unsigned int verify_patch_size(u8 family, u32 patch_size, unsigned int size)
{
u32 max_size;
@ -621,7 +625,12 @@ static int verify_and_add_patch(u8 family, u8 *fw, unsigned int leftover)
return crnt_size;
}
ret = verify_patch_size(family, patch_size, leftover);
/*
* The section header length is not included in this indicated size
* but is present in the leftover file length so we need to subtract
* it before passing this value to the function below.
*/
ret = verify_patch_size(family, patch_size, leftover - SECTION_HDR_SIZE);
if (!ret) {
pr_err("Patch-ID 0x%08x: size mismatch.\n", mc_hdr->patch_id);
return crnt_size;