# 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-8.1.0-nolibc/aarch64-linux/bin/aarch64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/aarch64-linux/bin/aarch64-linux-ld --version
# < git log --format=%s --max-count=1 7b55851367136b1efd84d98fea81ba57a98304cf
# < make -s -j 8 ARCH=arm64 O=/kisskb/build/linus_arm64-allmodconfig_arm64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/aarch64-linux/bin/aarch64-linux-  allmodconfig
# make -s -j 8 ARCH=arm64 O=/kisskb/build/linus_arm64-allmodconfig_arm64-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/aarch64-linux/bin/aarch64-linux-  
/kisskb/src/arch/arm64/boot/dts/rockchip/rk3399-gru-bob.dts:25.9-29.5: Warning (graph_port): /edp-panel/ports: graph port node name should be 'port'
/kisskb/src/arch/arm64/boot/dts/rockchip/rk3399-gru-kevin.dts:46.9-50.5: Warning (graph_port): /edp-panel/ports: graph port node name should be 'port'
/kisskb/src/arch/arm64/boot/dts/rockchip/rk3399-sapphire-excavator.dts:94.9-98.5: Warning (graph_port): /edp-panel/ports: graph port node name should be 'port'
In file included from /kisskb/src/include/asm-generic/bug.h:18,
                 from /kisskb/src/arch/arm64/include/asm/bug.h:37,
                 from /kisskb/src/include/linux/bug.h:5,
                 from /kisskb/src/include/linux/mmdebug.h:5,
                 from /kisskb/src/include/linux/mm.h:9,
                 from /kisskb/src/drivers/dma/imx-dma.c:14:
/kisskb/src/drivers/dma/imx-dma.c: In function 'imxdma_sg_next':
/kisskb/src/include/linux/kernel.h:846:29: warning: comparison of distinct pointer types lacks a cast
   (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                             ^~
/kisskb/src/include/linux/kernel.h:860:4: note: in expansion of macro '__typecheck'
   (__typecheck(x, y) && __no_side_effects(x, y))
    ^~~~~~~~~~~
/kisskb/src/include/linux/kernel.h:870:24: note: in expansion of macro '__safe_cmp'
  __builtin_choose_expr(__safe_cmp(x, y), \
                        ^~~~~~~~~~
/kisskb/src/include/linux/kernel.h:879:19: note: in expansion of macro '__careful_cmp'
 #define min(x, y) __careful_cmp(x, y, <)
                   ^~~~~~~~~~~~~
/kisskb/src/drivers/dma/imx-dma.c:288:8: note: in expansion of macro 'min'
  now = min(d->len, sg_dma_len(sg));
        ^~~
Completed OK
# rm -rf /kisskb/build/linus_arm64-allmodconfig_arm64-gcc8
# Build took: 0:30:41.479711