From: tip-bot for Borislav Petkov <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: bp@suse.de, linux-kernel@vger.kernel.org, mingo@kernel.org,
hpa@zytor.com, higuita@gmx.net, tglx@linutronix.de
Subject: [tip:x86/urgent] x86/microcode: Fix again accessing initrd after having been freed
Date: Wed, 24 Jan 2018 04:05:05 -0800 [thread overview]
Message-ID: <tip-1d080f096fe33f031d26e19b3ef0146f66b8b0f1@git.kernel.org> (raw)
In-Reply-To: <20180123104133.918-2-bp@alien8.de>
Commit-ID: 1d080f096fe33f031d26e19b3ef0146f66b8b0f1
Gitweb: https://git.kernel.org/tip/1d080f096fe33f031d26e19b3ef0146f66b8b0f1
Author: Borislav Petkov <bp@suse.de>
AuthorDate: Tue, 23 Jan 2018 11:41:33 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 24 Jan 2018 13:00:35 +0100
x86/microcode: Fix again accessing initrd after having been freed
Commit 24c2503255d3 ("x86/microcode: Do not access the initrd after it has
been freed") fixed attempts to access initrd from the microcode loader
after it has been freed. However, a similar KASAN warning was reported
(stack trace edited):
smpboot: Booting Node 0 Processor 1 APIC 0x11
==================================================================
BUG: KASAN: use-after-free in find_cpio_data+0x9b5/0xa50
Read of size 1 at addr ffff880035ffd000 by task swapper/1/0
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.14.8-slack #7
Hardware name: System manufacturer System Product Name/A88X-PLUS, BIOS 3003 03/10/2016
Call Trace:
dump_stack
print_address_description
kasan_report
? find_cpio_data
__asan_report_load1_noabort
find_cpio_data
find_microcode_in_initrd
__load_ucode_amd
load_ucode_amd_ap
load_ucode_ap
After some investigation, it turned out that a merge was done using the
wrong side to resolve, leading to picking up the previous state, before
the 24c2503255d3 fix. Therefore the Fixes tag below contains a merge
commit.
Revert the mismerge by catching the save_microcode_in_initrd_amd()
retval and thus letting the function exit with the last return statement
so that initrd_gone can be set to true.
Fixes: f26483eaedec ("Merge branch 'x86/urgent' into x86/microcode, to resolve conflicts")
Reported-by: <higuita@gmx.net>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=198295
Link: https://lkml.kernel.org/r/20180123104133.918-2-bp@alien8.de
---
arch/x86/kernel/cpu/microcode/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index c4fa4a8..e4fc595 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -239,7 +239,7 @@ static int __init save_microcode_in_initrd(void)
break;
case X86_VENDOR_AMD:
if (c->x86 >= 0x10)
- return save_microcode_in_initrd_amd(cpuid_eax(1));
+ ret = save_microcode_in_initrd_amd(cpuid_eax(1));
break;
default:
break;
prev parent reply other threads:[~2018-01-24 12:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-23 10:41 [PATCH 1/2] x86/microcode/intel: Extend BDW late-loading further with LLC size check Borislav Petkov
2018-01-23 10:41 ` [PATCH 2/2] x86/microcode: Fix again accessing initrd after having been freed Borislav Petkov
2018-01-24 12:05 ` tip-bot for Borislav Petkov [this message]
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