Buildresult: powerpc-fixes/pseries_defconfig+NO_MEMORY_HOTPLUG/powerpc-gcc5 built on Sep 4 2019, 22:21

kisskb

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Status:	OK
Date/Time:	Sep 4 2019, 22:21
Duration:	0:01:35.299450
Builder:	ka4
Revision:	powerpc/tm: Fix restoring FP/VMX facility incorrectly on interrupts (`457afdc0071dbd343a59426890b9677ca2882c23)`
Target:	powerpc-fixes/pseries_defconfig+NO_MEMORY_HOTPLUG/powerpc-gcc5
Branch:	powerpc-fixes
Compiler:	powerpc-gcc5 (powerpc64-linux-gcc (GCC) 5.5.0 / GNU ld (GNU Binutils) 2.29.1.20170915)
Config:	pseries_defconfig+NO_MEMORY_HOTPLUG (download)
Log:	Download original Possible warnings (1) kernel/futex.c:1676:17: warning: 'oldval' may be used uninitialized in this function [-Wmaybe-uninitialized] Full Log # git rev-parse -q --verify 457afdc0071dbd343a59426890b9677ca2882c23^{commit} 457afdc0071dbd343a59426890b9677ca2882c23 already have revision, skipping fetch # git checkout -q -f -B kisskb 457afdc0071dbd343a59426890b9677ca2882c23 # git clean -qxdf # < git log -1 # commit 457afdc0071dbd343a59426890b9677ca2882c23 # Author: Gustavo Romero <gromero@linux.ibm.com> # Date: Tue Sep 3 14:47:17 2019 +1000 # # powerpc/tm: Fix restoring FP/VMX facility incorrectly on interrupts # # When in userspace and MSR FP=0 the hardware FP state is unrelated to # the current process. This is extended for transactions where if tbegin # is run with FP=0, the hardware checkpoint FP state will also be # unrelated to the current process. Due to this, we need to ensure this # hardware checkpoint is updated with the correct state before we enable # FP for this process. # # Unfortunately we get this wrong when returning to a process from a # hardware interrupt. A process that starts a transaction with FP=0 can # take an interrupt. When the kernel returns back to that process, we # change to FP=1 but with hardware checkpoint FP state not updated. If # this transaction is then rolled back, the FP registers now contain the # wrong state. # # The process looks like this: # Userspace: Kernel # # Start userspace # with MSR FP=0 TM=1 # < ----- # ... # tbegin # bne # Hardware interrupt # ---- > # <do_IRQ...> # .... # ret_from_except # restore_math() # /* sees FP=0 / # restore_fp() # tm_active_with_fp() # / sees FP=1 (Incorrect) */ # load_fp_state() # FP = 0 -> 1 # < ----- # Return to userspace # with MSR TM=1 FP=1 # with junk in the FP TM checkpoint # TM rollback # reads FP junk # # When returning from the hardware exception, tm_active_with_fp() is # incorrectly making restore_fp() call load_fp_state() which is setting # FP=1. # # The fix is to remove tm_active_with_fp(). # # tm_active_with_fp() is attempting to handle the case where FP state # has been changed inside a transaction. In this case the checkpointed # and transactional FP state is different and hence we must restore the # FP state (ie. we can't do lazy FP restore inside a transaction that's # used FP). It's safe to remove tm_active_with_fp() as this case is # handled by restore_tm_state(). restore_tm_state() detects if FP has # been using inside a transaction and will set load_fp and call # restore_math() to ensure the FP state (checkpoint and transaction) is # restored. # # This is a data integrity problem for the current process as the FP # registers are corrupted. It's also a security problem as the FP # registers from one process may be leaked to another. # # Similarly for VMX. # # A simple testcase to replicate this will be posted to # tools/testing/selftests/powerpc/tm/tm-poison.c # # This fixes CVE-2019-15031. # # Fixes: a7771176b439 ("powerpc: Don't enable FP/Altivec if not checkpointed") # Cc: stable@vger.kernel.org # 4.15+ # Signed-off-by: Gustavo Romero <gromero@linux.ibm.com> # Signed-off-by: Michael Neuling <mikey@neuling.org> # Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> # Link: https://lore.kernel.org/r/20190903044718.13773-2-mikey@neuling.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 457afdc0071dbd343a59426890b9677ca2882c23 # < make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig+NO_MEMORY_HOTPLUG_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- pseries_defconfig # Added to kconfig CONFIG_MEMORY_HOTPLUG=n # Added to kconfig CONFIG_MEMORY_HOTREMOVE=n # yes \n \| make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig+NO_MEMORY_HOTPLUG_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 120 ARCH=powerpc O=/kisskb/build/powerpc-fixes_pseries_defconfig+NO_MEMORY_HOTPLUG_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- /kisskb/src/kernel/futex.c: In function 'do_futex': /kisskb/src/kernel/futex.c:1676:17: warning: 'oldval' may be used uninitialized in this function [-Wmaybe-uninitialized] return oldval == cmparg; ^ /kisskb/src/kernel/futex.c:1651:6: note: 'oldval' was declared here int oldval, ret; ^ Completed OK # rm -rf /kisskb/build/powerpc-fixes_pseries_defconfig+NO_MEMORY_HOTPLUG_powerpc-gcc5 # Build took: 0:01:35.299450

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