On 09/07/2017 06:36 PM, Greg Thelen wrote: > __get_request() can call trace_block_getrq() with bio=NULL which causes > block_get_rq::TP_fast_assign() to deref a NULL pointer and panic. > > Syzkaller fuzzer panics with > linux-next (1d53d908b79d7870d89063062584eead4cf83448): > kasan: GPF could be caused by NULL-ptr deref or user memory access > general protection fault: 0000 [#1] SMP KASAN > Modules linked in: > CPU: 0 PID: 2983 Comm: syzkaller401111 Not tainted 4.13.0-rc7-next-20170901+ #13 > task: ffff8801cf1da000 task.stack: ffff8801ce440000 > RIP: 0010:perf_trace_block_get_rq+0x697/0x970 include/trace/events/block.h:384 > RSP: 0018:ffff8801ce4473f0 EFLAGS: 00010246 > RAX: ffff8801cf1da000 RBX: 1ffff10039c88e84 RCX: 1ffffd1ffff84d27 > RDX: dffffc0000000001 RSI: 1ffff1003b643e7a RDI: ffffe8ffffc26938 > RBP: ffff8801ce447530 R08: 1ffff1003b643e6c R09: ffffe8ffffc26964 > R10: 0000000000000002 R11: fffff91ffff84d2d R12: ffffe8ffffc1f890 > R13: ffffe8ffffc26930 R14: ffffffff85cad9e0 R15: 0000000000000000 > FS: 0000000002641880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000000000043e670 CR3: 00000001d1d7a000 CR4: 00000000001406f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > trace_block_getrq include/trace/events/block.h:423 [inline] > __get_request block/blk-core.c:1283 [inline] > get_request+0x1518/0x23b0 block/blk-core.c:1355 > blk_old_get_request block/blk-core.c:1402 [inline] > blk_get_request+0x1d8/0x3c0 block/blk-core.c:1427 > sg_scsi_ioctl+0x117/0x750 block/scsi_ioctl.c:451 > sg_ioctl+0x192d/0x2ed0 drivers/scsi/sg.c:1070 > vfs_ioctl fs/ioctl.c:45 [inline] > do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685 > SYSC_ioctl fs/ioctl.c:700 [inline] > SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 > entry_SYSCALL_64_fastpath+0x1f/0xbe > > block_get_rq::TP_fast_assign() has multiple redundant ->dev assignments. > Only one of them is NULL tolerant. Favor the NULL tolerant one. Applied, thanks. -- Jens Axboe
