Skip to main content

Browse the archive

https://github.com/torvalds/linux
27 March 2024, 02:37:15 UTC
Revision fc152d22d6e9fac95a9a990e6c29510bdf1b9425 authored by Mateusz Jurczyk on 24 May 2017, 13:55:00 UTC, committed by Thomas Gleixner on 24 May 2017, 14:18:12 UTC 
x86/alternatives: Prevent uninitialized stack byte read in apply_alternatives()
 
In the current form of the code, if a->replacementlen is 0, the reference
to *insnbuf for comparison touches potentially garbage memory. While it
doesn't affect the execution flow due to the subsequent a->replacementlen
comparison, it is (rightly) detected as use of uninitialized memory by a
runtime instrumentation currently under my development, and could be
detected as such by other tools in the future, too (e.g. KMSAN).

Fix the "false-positive" by reordering the conditions to first check the
replacement instruction length before referencing specific opcode bytes.

Signed-off-by: Mateusz Jurczyk <mjurczyk@google.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Link: http://lkml.kernel.org/r/20170524135500.27223-1-mjurczyk@google.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
1 parent cbed27c
History
Tip revision: fc152d22d6e9fac95a9a990e6c29510bdf1b9425 authored by Mateusz Jurczyk on 24 May 2017, 13:55:00 UTC
x86/alternatives: Prevent uninitialized stack byte read in apply_alternatives()
Tip revision: fc152d2
File Mode Size
Documentation
arch
block
certs
crypto
drivers
firmware
fs
include
init
ipc
kernel
lib
mm
net
samples
scripts
security
sound
tools
usr
virt
.cocciconfig -rw-r--r-- 59 bytes
.get_maintainer.ignore -rw-r--r-- 31 bytes
.gitattributes -rw-r--r-- 30 bytes
.gitignore -rw-r--r-- 1.3 KB
.mailmap -rw-r--r-- 8.1 KB
COPYING -rw-r--r-- 18.3 KB
CREDITS -rw-r--r-- 96.2 KB
Kbuild -rw-r--r-- 2.2 KB
Kconfig -rw-r--r-- 252 bytes
MAINTAINERS -rw-r--r-- 397.7 KB
Makefile -rw-r--r-- 58.6 KB
README -rw-r--r-- 722 bytes

README

back to top