# git rev-parse -q --verify 7b55851367136b1efd84d98fea81ba57a98304cf^{commit}
7b55851367136b1efd84d98fea81ba57a98304cf
already have revision, skipping fetch
# git checkout -q -f -B kisskb 7b55851367136b1efd84d98fea81ba57a98304cf
# git clean -qxdf
# < git log -1
# commit 7b55851367136b1efd84d98fea81ba57a98304cf
# Author: David Herrmann <dh.herrmann@gmail.com>
# Date:   Tue Jan 8 13:58:52 2019 +0100
# 
#     fork: record start_time late
#     
#     This changes the fork(2) syscall to record the process start_time after
#     initializing the basic task structure but still before making the new
#     process visible to user-space.
#     
#     Technically, we could record the start_time anytime during fork(2).  But
#     this might lead to scenarios where a start_time is recorded long before
#     a process becomes visible to user-space.  For instance, with
#     userfaultfd(2) and TLS, user-space can delay the execution of fork(2)
#     for an indefinite amount of time (and will, if this causes network
#     access, or similar).
#     
#     By recording the start_time late, it much closer reflects the point in
#     time where the process becomes live and can be observed by other
#     processes.
#     
#     Lastly, this makes it much harder for user-space to predict and control
#     the start_time they get assigned.  Previously, user-space could fork a
#     process and stall it in copy_thread_tls() before its pid is allocated,
#     but after its start_time is recorded.  This can be misused to later-on
#     cycle through PIDs and resume the stalled fork(2) yielding a process
#     that has the same pid and start_time as a process that existed before.
#     This can be used to circumvent security systems that identify processes
#     by their pid+start_time combination.
#     
#     Even though user-space was always aware that start_time recording is
#     flaky (but several projects are known to still rely on start_time-based
#     identification), changing the start_time to be recorded late will help
#     mitigate existing attacks and make it much harder for user-space to
#     control the start_time a process gets assigned.
#     
#     Reported-by: Jann Horn <jannh@google.com>
#     Signed-off-by: Tom Gundersen <teg@jklm.no>
#     Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
#     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
# < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version
# < git log --format=%s --max-count=1 7b55851367136b1efd84d98fea81ba57a98304cf
# < make -s -j 8 ARCH=powerpc O=/kisskb/build/linus-rand_powerpc-randconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  randconfig
KCONFIG_SEED=0x9B59F866
# Added to kconfig CONFIG_STANDALONE=y
# Added to kconfig CONFIG_BUILD_DOCSRC=n
# Added to kconfig CONFIG_MODULE_SIG=n
# Added to kconfig CONFIG_CPU_BIG_ENDIAN=y
# Added to kconfig CONFIG_PPC64=y
# Added to kconfig CONFIG_PPC_DISABLE_WERROR=y
# Added to kconfig CONFIG_SECTION_MISMATCH_WARN_ONLY=y
# Added to kconfig CONFIG_PREVENT_FIRMWARE_BUILD=y
# Added to kconfig CONFIG_CC_STACKPROTECTOR_STRONG=n
# Added to kconfig CONFIG_GCC_PLUGINS=n
# Added to kconfig CONFIG_LD_HEAD_STUB_CATCH=y
# Added to kconfig 
# yes \n | make -s -j 8 ARCH=powerpc O=/kisskb/build/linus-rand_powerpc-randconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  oldconfig
yes: standard output: Broken pipe
# make -s -j 8 ARCH=powerpc O=/kisskb/build/linus-rand_powerpc-randconfig_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
/kisskb/src/fs/jffs2/xattr.c: In function 'jffs2_build_xattr_subsystem':
/kisskb/src/fs/jffs2/xattr.c:887:1: warning: the frame size of 1072 bytes is larger than 1024 bytes [-Wframe-larger-than=]
 }
 ^
/kisskb/src/drivers/md/dm-writecache.c: In function 'persistent_memory_claim':
/kisskb/src/drivers/md/dm-writecache.c:312:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
Completed OK
# rm -rf /kisskb/build/linus-rand_powerpc-randconfig_powerpc-gcc5
# Build took: 0:04:18.691181