Buildresult: linus/parisc-allnoconfig/parisc-gcc8 built on Jan 9 2019, 16:06

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Status:	OK
Date/Time:	Jan 9 2019, 16:06
Duration:	0:00:17.822863
Builder:	ka2
Revision:	fork: record start_time late (`7b55851367136b1efd84d98fea81ba57a98304cf)`
Target:	linus/parisc-allnoconfig/parisc-gcc8
Branch:	linus
Compiler:	parisc-gcc8 (hppa-linux-gcc (GCC) 8.1.0 / GNU ld (GNU Binutils) 2.30)
Config:	allnoconfig (download)
Log:	Download original Possible warnings (2) <stdin>:1336:2: warning: #warning syscall rseq not implemented [-Wcpp] arch/parisc/kernel/pci-dma.c:334:12: warning: 'proc_pcxl_dma_show' defined but not used [-Wunused-function] Full Log # 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/hppa-linux/bin/hppa-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa-linux/bin/hppa-linux-ld --version # < git log --format=%s --max-count=1 7b55851367136b1efd84d98fea81ba57a98304cf # < make -s -j 8 ARCH=parisc O=/kisskb/build/linus_parisc-allnoconfig_parisc CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa-linux/bin/hppa-linux- allnoconfig # make -s -j 8 ARCH=parisc O=/kisskb/build/linus_parisc-allnoconfig_parisc CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/hppa-linux/bin/hppa-linux- <stdin>:1336:2: warning: #warning syscall rseq not implemented [-Wcpp] /kisskb/src/arch/parisc/kernel/pci-dma.c:334:12: warning: 'proc_pcxl_dma_show' defined but not used [-Wunused-function] static int proc_pcxl_dma_show(struct seq_file m, void v) ^~~~~~~~~~~~~~~~~~ Completed OK # rm -rf /kisskb/build/linus_parisc-allnoconfig_parisc # Build took: 0:00:17.822863

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