# git rev-parse -q --verify a68a0262abdaa251e12c53715f48e698a18ef402^{commit}
a68a0262abdaa251e12c53715f48e698a18ef402
already have revision, skipping fetch
# git checkout -q -f -B kisskb a68a0262abdaa251e12c53715f48e698a18ef402
# git clean -qxdf
# < git log -1
# commit a68a0262abdaa251e12c53715f48e698a18ef402
# Author: Minchan Kim <minchan@kernel.org>
# Date:   Tue Dec 8 20:57:18 2020 -0800
# 
#     mm/madvise: remove racy mm ownership check
#     
#     Jann spotted the security hole due to race of mm ownership check.
#     
#     If the task is sharing the mm_struct but goes through execve() before
#     mm_access(), it could skip process_madvise_behavior_valid check.  That
#     makes *any advice hint* to reach into the remote process.
#     
#     This patch removes the mm ownership check.  With it, it will lose the
#     ability that local process could give *any* advice hint with vector
#     interface for some reason (e.g., performance).  Since there is no
#     concrete example in upstream yet, it would be better to remove the
#     abiliity at this moment and need to review when such new advice comes
#     up.
#     
#     Fixes: ecb8ac8b1f14 ("mm/madvise: introduce process_madvise() syscall: an external memory hinting API")
#     Reported-by: Jann Horn <jannh@google.com>
#     Suggested-by: Jann Horn <jannh@google.com>
#     Signed-off-by: Minchan Kim <minchan@kernel.org>
#     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
# < /opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux-gcc --version
# < /opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux-ld --version
# < git log --format=%s --max-count=1 a68a0262abdaa251e12c53715f48e698a18ef402
# < make -s -j 10 ARCH=um O=/kisskb/build/linus_um-defconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 defconfig
# < make -s -j 10 ARCH=um O=/kisskb/build/linus_um-defconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 help
# make -s -j 10 ARCH=um O=/kisskb/build/linus_um-defconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 olddefconfig
# make -s -j 10 ARCH=um O=/kisskb/build/linus_um-defconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 
/kisskb/src/arch/um/os-Linux/signal.c: In function 'sig_handler_common':
/kisskb/src/arch/um/os-Linux/signal.c:51:1: warning: the frame size of 2960 bytes is larger than 1024 bytes [-Wframe-larger-than=]
 }
 ^
/kisskb/src/arch/um/os-Linux/signal.c: In function 'timer_real_alarm_handler':
/kisskb/src/arch/um/os-Linux/signal.c:95:1: warning: the frame size of 2960 bytes is larger than 1024 bytes [-Wframe-larger-than=]
 }
 ^
  LINK linux
Completed OK
# rm -rf /kisskb/build/linus_um-defconfig_um-x86_64
# Build took: 0:01:29.579704