# git rev-parse -q --verify 5eedf9fe8db23313df104576845cec5f481b9b60^{commit} 5eedf9fe8db23313df104576845cec5f481b9b60 already have revision, skipping fetch # git checkout -q -f -B kisskb 5eedf9fe8db23313df104576845cec5f481b9b60 # git clean -qxdf # < git log -1 # commit 5eedf9fe8db23313df104576845cec5f481b9b60 # Author: Christophe Leroy # Date: Mon Dec 7 16:58:01 2020 +0000 # # powerpc/mm: Fix KUAP warning by providing copy_from_kernel_nofault_allowed() # # Since commit c33165253492 ("powerpc: use non-set_fs based maccess # routines"), userspace access is not granted anymore when using # copy_from_kernel_nofault() # # However, kthread_probe_data() uses copy_from_kernel_nofault() # to check validity of pointers. When the pointer is NULL, # it points to userspace, leading to a KUAP fault and triggering # the following big hammer warning many times when you request # a sysrq "show task": # # [ 1117.202054] ------------[ cut here ]------------ # [ 1117.202102] Bug: fault blocked by AP register ! # [ 1117.202261] WARNING: CPU: 0 PID: 377 at arch/powerpc/include/asm/nohash/32/kup-8xx.h:66 do_page_fault+0x4a8/0x5ec # [ 1117.202310] Modules linked in: # [ 1117.202428] CPU: 0 PID: 377 Comm: sh Tainted: G W 5.10.0-rc5-01340-g83f53be2de31-dirty #4175 # [ 1117.202499] NIP: c0012048 LR: c0012048 CTR: 00000000 # [ 1117.202573] REGS: cacdbb88 TRAP: 0700 Tainted: G W (5.10.0-rc5-01340-g83f53be2de31-dirty) # [ 1117.202625] MSR: 00021032 CR: 24082222 XER: 20000000 # [ 1117.202899] # [ 1117.202899] GPR00: c0012048 cacdbc40 c2929290 00000023 c092e554 00000001 c09865e8 c092e640 # [ 1117.202899] GPR08: 00001032 00000000 00000000 00014efc 28082224 100d166a 100a0920 00000000 # [ 1117.202899] GPR16: 100cac0c 100b0000 1080c3fc 1080d685 100d0000 100d0000 00000000 100a0900 # [ 1117.202899] GPR24: 100d0000 c07892ec 00000000 c0921510 c21f4440 0000005c c0000000 cacdbc80 # [ 1117.204362] NIP [c0012048] do_page_fault+0x4a8/0x5ec # [ 1117.204461] LR [c0012048] do_page_fault+0x4a8/0x5ec # [ 1117.204509] Call Trace: # [ 1117.204609] [cacdbc40] [c0012048] do_page_fault+0x4a8/0x5ec (unreliable) # [ 1117.204771] [cacdbc70] [c00112f0] handle_page_fault+0x8/0x34 # [ 1117.204911] --- interrupt: 301 at copy_from_kernel_nofault+0x70/0x1c0 # [ 1117.204979] NIP: c010dbec LR: c010dbac CTR: 00000001 # [ 1117.205053] REGS: cacdbc80 TRAP: 0301 Tainted: G W (5.10.0-rc5-01340-g83f53be2de31-dirty) # [ 1117.205104] MSR: 00009032 CR: 28082224 XER: 00000000 # [ 1117.205416] DAR: 0000005c DSISR: c0000000 # [ 1117.205416] GPR00: c0045948 cacdbd38 c2929290 00000001 00000017 00000017 00000027 0000000f # [ 1117.205416] GPR08: c09926ec 00000000 00000000 3ffff000 24082224 # [ 1117.206106] NIP [c010dbec] copy_from_kernel_nofault+0x70/0x1c0 # [ 1117.206202] LR [c010dbac] copy_from_kernel_nofault+0x30/0x1c0 # [ 1117.206258] --- interrupt: 301 # [ 1117.206372] [cacdbd38] [c004bbb0] kthread_probe_data+0x44/0x70 (unreliable) # [ 1117.206561] [cacdbd58] [c0045948] print_worker_info+0xe0/0x194 # [ 1117.206717] [cacdbdb8] [c00548ac] sched_show_task+0x134/0x168 # [ 1117.206851] [cacdbdd8] [c005a268] show_state_filter+0x70/0x100 # [ 1117.206989] [cacdbe08] [c039baa0] sysrq_handle_showstate+0x14/0x24 # [ 1117.207122] [cacdbe18] [c039bf18] __handle_sysrq+0xac/0x1d0 # [ 1117.207257] [cacdbe48] [c039c0c0] write_sysrq_trigger+0x4c/0x74 # [ 1117.207407] [cacdbe68] [c01fba48] proc_reg_write+0xb4/0x114 # [ 1117.207550] [cacdbe88] [c0179968] vfs_write+0x12c/0x478 # [ 1117.207686] [cacdbf08] [c0179e60] ksys_write+0x78/0x128 # [ 1117.207826] [cacdbf38] [c00110d0] ret_from_syscall+0x0/0x34 # [ 1117.207938] --- interrupt: c01 at 0xfd4e784 # [ 1117.208008] NIP: 0fd4e784 LR: 0fe0f244 CTR: 10048d38 # [ 1117.208083] REGS: cacdbf48 TRAP: 0c01 Tainted: G W (5.10.0-rc5-01340-g83f53be2de31-dirty) # [ 1117.208134] MSR: 0000d032 CR: 44002222 XER: 00000000 # [ 1117.208470] # [ 1117.208470] GPR00: 00000004 7fc34090 77bfb4e0 00000001 1080fa40 00000002 7400000f fefefeff # [ 1117.208470] GPR08: 7f7f7f7f 10048d38 1080c414 7fc343c0 00000000 # [ 1117.209104] NIP [0fd4e784] 0xfd4e784 # [ 1117.209180] LR [0fe0f244] 0xfe0f244 # [ 1117.209236] --- interrupt: c01 # [ 1117.209274] Instruction dump: # [ 1117.209353] 714a4000 418200f0 73ca0001 40820084 73ca0032 408200f8 73c90040 4082ff60 # [ 1117.209727] 0fe00000 3c60c082 386399f4 48013b65 <0fe00000> 80010034 3860000b 7c0803a6 # [ 1117.210102] ---[ end trace 1927c0323393af3e ]--- # # To avoid that, copy_from_kernel_nofault_allowed() is used to check # whether the address is a valid kernel address. But the default # version of it returns true for any address. # # Provide a powerpc version of copy_from_kernel_nofault_allowed() # that returns false when the address is below TASK_USER_MAX, # so that copy_from_kernel_nofault() will return -ERANGE. # # Fixes: c33165253492 ("powerpc: use non-set_fs based maccess routines") # Reported-by: Qian Cai # Signed-off-by: Christophe Leroy # Signed-off-by: Michael Ellerman # Link: https://lore.kernel.org/r/18bcb456d32a3e74f5ae241fd6f1580c092d07f5.1607360230.git.christophe.leroy@csgroup.eu # < /opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version # < git log --format=%s --max-count=1 5eedf9fe8db23313df104576845cec5f481b9b60 # < make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_44x_bamboo_defconfig_powerpc-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux- 44x/bamboo_defconfig # < make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_44x_bamboo_defconfig_powerpc-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux- help # make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_44x_bamboo_defconfig_powerpc-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux- olddefconfig # make -s -j 24 ARCH=powerpc O=/kisskb/build/powerpc-fixes_44x_bamboo_defconfig_powerpc-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/powerpc64-linux/bin/powerpc64-linux- /kisskb/src/block/genhd.c: In function 'diskstats_show': /kisskb/src/block/genhd.c:1659:1: warning: the frame size of 1160 bytes is larger than 1024 bytes [-Wframe-larger-than=] } ^ INFO: Uncompressed kernel (size 0x4e2f08) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x500000) INFO: Uncompressed kernel (size 0x4e2f08) overlaps the address of the wrapper(0x400000) INFO: Fixing the link_address of wrapper to (0x500000) Image Name: Linux-5.10.0-rc2-g5eedf9fe8db2 Created: Wed Dec 9 02:06:22 2020 Image Type: PowerPC Linux Kernel Image (gzip compressed) Data Size: 2494885 Bytes = 2436.41 KiB = 2.38 MiB Load Address: 00500000 Entry Point: 005001b8 Completed OK # rm -rf /kisskb/build/powerpc-fixes_44x_bamboo_defconfig_powerpc-gcc4.9 # Build took: 0:00:53.291855