# git rev-parse -q --verify b1ad106c02e19d81927b5a522167780525569490^{commit} b1ad106c02e19d81927b5a522167780525569490 already have revision, skipping fetch # git checkout -q -f -B kisskb b1ad106c02e19d81927b5a522167780525569490 # git clean -qxdf # < git log -1 # commit b1ad106c02e19d81927b5a522167780525569490 # Author: Michael Ellerman # Date: Tue Mar 3 23:28:47 2020 +1100 # # powerpc/mm: Fix missing KUAP disable in flush_coherent_icache() # # We received a report of strange kernel faults which turned out to be # due to a missing KUAP disable in flush_coherent_icache() called # from flush_icache_range(). # # The fault looks like: # # Kernel attempted to access user page (7fffc30d9c00) - exploit attempt? (uid: 1009) # BUG: Unable to handle kernel data access on read at 0x7fffc30d9c00 # Faulting instruction address: 0xc00000000007232c # Oops: Kernel access of bad area, sig: 11 [#1] # LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA PowerNV # CPU: 35 PID: 5886 Comm: sigtramp Not tainted 5.6.0-rc2-gcc-8.2.0-00003-gfc37a1632d40 #79 # NIP: c00000000007232c LR: c00000000003b7fc CTR: 0000000000000000 # REGS: c000001e11093940 TRAP: 0300 Not tainted (5.6.0-rc2-gcc-8.2.0-00003-gfc37a1632d40) # MSR: 900000000280b033 CR: 28000884 XER: 00000000 # CFAR: c0000000000722fc DAR: 00007fffc30d9c00 DSISR: 08000000 IRQMASK: 0 # GPR00: c00000000003b7fc c000001e11093bd0 c0000000023ac200 00007fffc30d9c00 # GPR04: 00007fffc30d9c18 0000000000000000 c000001e11093bd4 0000000000000000 # GPR08: 0000000000000000 0000000000000001 0000000000000000 c000001e1104ed80 # GPR12: 0000000000000000 c000001fff6ab380 c0000000016be2d0 4000000000000000 # GPR16: c000000000000000 bfffffffffffffff 0000000000000000 0000000000000000 # GPR20: 00007fffc30d9c00 00007fffc30d8f58 00007fffc30d9c18 00007fffc30d9c20 # GPR24: 00007fffc30d9c18 0000000000000000 c000001e11093d90 c000001e1104ed80 # GPR28: c000001e11093e90 0000000000000000 c0000000023d9d18 00007fffc30d9c00 # NIP flush_icache_range+0x5c/0x80 # LR handle_rt_signal64+0x95c/0xc2c # Call Trace: # 0xc000001e11093d90 (unreliable) # handle_rt_signal64+0x93c/0xc2c # do_notify_resume+0x310/0x430 # ret_from_except_lite+0x70/0x74 # Instruction dump: # 409e002c 7c0802a6 3c62ff31 3863f6a0 f8010080 48195fed 60000000 48fe4c8d # 60000000 e8010080 7c0803a6 7c0004ac <7c00ffac> 7c0004ac 4c00012c 38210070 # # This path through handle_rt_signal64() to setup_trampoline() and # flush_icache_range() is only triggered by 64-bit processes that have # unmapped their VDSO, which is rare. # # flush_icache_range() takes a range of addresses to flush. In # flush_coherent_icache() we implement an optimisation for CPUs where we # know we don't actually have to flush the whole range, we just need to # do a single icbi. # # However we still execute the icbi on the user address of the start of # the range we're flushing. On CPUs that also implement KUAP (Power9) # that leads to the spurious fault above. # # We should be able to pass any address, including a kernel address, to # the icbi on these CPUs, which would avoid any interaction with KUAP. # But I don't want to make that change in a bug fix, just in case it # surfaces some strange behaviour on some CPU. # # So for now just disable KUAP around the icbi. Note the icbi is treated # as a load, so we allow read access, not write as you'd expect. # # Fixes: 890274c2dc4c ("powerpc/64s: Implement KUAP for Radix MMU") # Cc: stable@vger.kernel.org # v5.2+ # Signed-off-by: Michael Ellerman # < /opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux-ld --version # < git log --format=%s --max-count=1 b1ad106c02e19d81927b5a522167780525569490 # < make -s -j 48 ARCH=mips O=/kisskb/build/powerpc-fixes_mips-defconfig_mips-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux- defconfig # < make -s -j 48 ARCH=mips O=/kisskb/build/powerpc-fixes_mips-defconfig_mips-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux- help # make -s -j 48 ARCH=mips O=/kisskb/build/powerpc-fixes_mips-defconfig_mips-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux- olddefconfig # make -s -j 48 ARCH=mips O=/kisskb/build/powerpc-fixes_mips-defconfig_mips-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/mips-linux/bin/mips-linux- FIT description: Linux 5.6.0-rc2-00014-gb1ad106c02e1 Created: Wed Mar 4 01:55:28 2020 Image 0 (kernel@0) Description: Linux 5.6.0-rc2-00014-gb1ad106c02e1 Created: Wed Mar 4 01:55:28 2020 Type: Kernel Image Compression: gzip compressed Data Size: 4906328 Bytes = 4791.34 KiB = 4.68 MiB Architecture: MIPS OS: Linux Load Address: 0x80100000 Entry Point: 0x808ffe70 Hash algo: sha1 Hash value: 497489ef7444fc072cda640f2a60401bb0712e89 Image 1 (fdt@boston) Description: img,boston Device Tree Created: Wed Mar 4 01:55:28 2020 Type: Flat Device Tree Compression: uncompressed Data Size: 3793 Bytes = 3.70 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 4799f50d688573234da6e9d7701234d394759ef4 Image 2 (fdt@ni169445) Description: NI 169445 device tree Created: Wed Mar 4 01:55:28 2020 Type: Flat Device Tree Compression: uncompressed Data Size: 1871 Bytes = 1.83 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 51b89b31605ee62038c8468c429af091dfc75ec7 Image 3 (fdt@ocelot_pcb123) Description: MSCC Ocelot PCB123 Device Tree Created: Wed Mar 4 01:55:28 2020 Type: Flat Device Tree Compression: uncompressed Data Size: 4639 Bytes = 4.53 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 018897896b42c41c943aca35a20e4300dba250c8 Image 4 (fdt@ocelot_pcb120) Description: MSCC Ocelot PCB120 Device Tree Created: Wed Mar 4 01:55:28 2020 Type: Flat Device Tree Compression: uncompressed Data Size: 5198 Bytes = 5.08 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 36c7bd0bd79cfc2f7dd6acda6c7996294f4967e6 Image 5 (fdt@xilfpga) Description: MIPSfpga (xilfpga) Device Tree Created: Wed Mar 4 01:55:28 2020 Type: Flat Device Tree Compression: uncompressed Data Size: 2708 Bytes = 2.64 KiB = 0.00 MiB Architecture: MIPS Hash algo: sha1 Hash value: 63d058b780f65e22da30f0a183433765f1807f1d Default Configuration: 'conf@default' Configuration 0 (conf@default) Description: Generic Linux kernel Kernel: kernel@0 Configuration 1 (conf@boston) Description: Boston Linux kernel Kernel: kernel@0 FDT: fdt@boston Configuration 2 (conf@ni169445) Description: NI 169445 Linux Kernel Kernel: kernel@0 FDT: fdt@ni169445 Configuration 3 (conf@ocelot_pcb123) Description: Ocelot Linux kernel Kernel: kernel@0 FDT: fdt@ocelot_pcb123 Configuration 4 (conf@ocelot_pcb120) Description: Ocelot Linux kernel Kernel: kernel@0 FDT: fdt@ocelot_pcb120 Configuration 5 (conf@xilfpga) Description: MIPSfpga Linux kernel Kernel: kernel@0 FDT: fdt@xilfpga Completed OK # rm -rf /kisskb/build/powerpc-fixes_mips-defconfig_mips-gcc4.9 # Build took: 0:01:34.531833