# git rev-parse -q --verify 3bf9c3bd86cdde4aa4d12c2705d93e1d90464710^{commit} 3bf9c3bd86cdde4aa4d12c2705d93e1d90464710 already have revision, skipping fetch # git checkout -q -f -B kisskb 3bf9c3bd86cdde4aa4d12c2705d93e1d90464710 # git clean -qxdf # < git log -1 # commit 3bf9c3bd86cdde4aa4d12c2705d93e1d90464710 # Author: Frederic Barrat # Date: Mon Jun 24 16:41:48 2019 +0200 # # ocxl: Fix concurrent AFU open and device removal # # If an ocxl device is unbound through sysfs at the same time its AFU is # being opened by a user process, the open code may dereference freed # stuctures, which can lead to kernel oops messages. You'd have to hit a # tiny time window, but it's possible. It's fairly easy to test by # making the time window bigger artificially. # # Fix it with a combination of 2 changes: # - when an AFU device is found in the IDR by looking for the device # minor number, we should hold a reference on the device until after # the context is allocated. A reference on the AFU structure is kept # when the context is allocated, so we can release the reference on # the device after the context allocation. # - with the fix above, there's still another even tinier window, # between the time the AFU device is found in the IDR and the # reference on the device is taken. We can fix this one by removing # the IDR entry earlier, when the device setup is removed, instead # of waiting for the 'release' device callback. With proper locking # around the IDR. # # Fixes: 75ca758adbaf ("ocxl: Create a clear delineation between ocxl backend & frontend") # Cc: stable@vger.kernel.org # v5.2+ # Signed-off-by: Frederic Barrat # Reviewed-by: Greg Kurz # Signed-off-by: Michael Ellerman # Link: https://lore.kernel.org/r/20190624144148.32022-1-fbarrat@linux.ibm.com # < /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 3bf9c3bd86cdde4aa4d12c2705d93e1d90464710 # < make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_ppc64_defconfig+UP_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- ppc64_defconfig # Added to kconfig CONFIG_SMP=n # yes \n | make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_ppc64_defconfig+UP_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 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_ppc64_defconfig+UP_powerpc-gcc5 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-5.5.0-nolibc/powerpc64-linux/bin/powerpc64-linux- WARNING: 2 bad relocations c00000000199d480 R_PPC64_ADDR64 _binary__btf_vmlinux_bin_start c00000000199d488 R_PPC64_ADDR64 _binary__btf_vmlinux_bin_end Completed OK # rm -rf /kisskb/build/powerpc-fixes_ppc64_defconfig+UP_powerpc-gcc5 # Build took: 0:03:55.338625