lkml.org 
[lkml]   [2022]   [Dec]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 2/2] x86/microcode/AMD: Handle multiple glued containers properly
Date
From: Borislav Petkov <bp@suse.de>

It can happen that - especially during testing - the microcode
blobs of all families are all glued together in the initrd. The
current code doesn't check whether the current container matched
a microcode patch and continues to the next one, which leads to
save_microcode_in_initrd_amd() to look at the next and thus wrong one:

microcode: parse_container: ucode: 0xffff88807e9d9082
microcode: verify_patch: buf: 0xffff88807e9d90ce, buf_size: 26428
microcode: verify_patch: proc_id: 0x8082, patch_fam: 0x17, this family: 0x17
microcode: verify_patch: buf: 0xffff88807e9d9d56, buf_size: 23220
microcode: verify_patch: proc_id: 0x8012, patch_fam: 0x17, this family: 0x17
microcode: parse_container: MATCH: eq_id: 0x8012, patch proc_rev_id: 0x8012

<-- matching patch found

microcode: verify_patch: buf: 0xffff88807e9da9de, buf_size: 20012
microcode: verify_patch: proc_id: 0x8310, patch_fam: 0x17, this family: 0x17
microcode: verify_patch: buf: 0xffff88807e9db666, buf_size: 16804
microcode: Invalid type field (0x414d44) in container file section header.
microcode: Patch section fail

<-- checking chokes on the microcode magic value of the next container.

microcode: parse_container: saving container 0xffff88807e9d9082
microcode: save_microcode_in_initrd_amd: scanned containers, data: 0xffff88807e9d9082, size: 9700a

and now if there's a next (and last container) it'll use that in
save_microcode_in_initrd_amd() and not find a proper patch, ofc.

Fix that by moving the out: label up, before the desc->mc check which
jots down the pointer of the matching patch and is used to signal to the
caller that it has found a matching patch in the current container.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/cpu/microcode/amd.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c
index 339c9666c8bc..d144f918a896 100644
--- a/arch/x86/kernel/cpu/microcode/amd.c
+++ b/arch/x86/kernel/cpu/microcode/amd.c
@@ -330,8 +330,9 @@ static size_t parse_container(u8 *ucode, size_t size, struct cont_desc *desc)
ret = verify_patch(x86_family(desc->cpuid_1_eax), buf, size, &patch_size, true);
if (ret < 0) {
/*
- * Patch verification failed, skip to the next
- * container, if there's one:
+ * Patch verification failed, skip to the next container, if
+ * there is one. Before exit, check whether that container has
+ * found a patch already. If so, use it.
*/
goto out;
} else if (ret > 0) {
@@ -350,6 +351,7 @@ static size_t parse_container(u8 *ucode, size_t size, struct cont_desc *desc)
size -= patch_size + SECTION_HDR_SIZE;
}

+out:
/*
* If we have found a patch (desc->mc), it means we're looking at the
* container which has a patch for this CPU so return 0 to mean, @ucode
@@ -364,7 +366,6 @@ static size_t parse_container(u8 *ucode, size_t size, struct cont_desc *desc)
return 0;
}

-out:
return orig_size - size;
}

--
2.35.1
\
 
 \ /
  Last update: 2023-03-26 23:15    [W:0.038 / U:0.564 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site