Syzbot has reported the following splat triggered by fault injection: kernel BUG at lib/iov_iter.c:624! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 0 UID: 0 PID: 5767 Comm: repro Not tainted 6.12.0-rc4-syzkaller-00261-g850925a8133c #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014 RIP: 0010:iov_iter_revert+0x420/0x590 Code: 42 80 3c 20 00 48 8b 1c 24 74 08 48 89 df e8 17 07 43 fd 4c 89 2b e9 04 01 00 00 45 85 ed 48 8b 3c 24 75 16 e8 41 48 d9 fc 90 <0f> 0b 41 83 fd 05 48 8b 3c 24 0f 84 58 01 00 00 48 89 f8 48 c1 e8 RSP: 0018:ffffc90002f4f740 EFLAGS: 00010293 RAX: ffffffff84bba22f RBX: 000000000001e098 RCX: ffff888026309cc0 RDX: 0000000000000000 RSI: ffffffff8f098180 RDI: ffff888024f92df0 RBP: 0000000000000000 R08: 0000000000000001 R09: ffffffff84bb9f14 R10: 0000000000000004 R11: ffff888026309cc0 R12: dffffc0000000000 R13: 0000000000000000 R14: ffff888024f92de0 R15: fffffffffffe1f68 FS: 00007f2c11757600(0000) GS:ffff888062800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000557cafd1eb48 CR3: 0000000024e1a000 CR4: 00000000000006f0 Call Trace: <TASK> ? __die_body+0x5f/0xb0 ? die+0x9e/0xc0 ? do_trap+0x15a/0x3a0 ? iov_iter_revert+0x420/0x590 ? do_error_trap+0x1dc/0x2c0 ? iov_iter_revert+0x420/0x590 ? __pfx_do_error_trap+0x10/0x10 ? handle_invalid_op+0x34/0x40 ? iov_iter_revert+0x420/0x590 ? exc_invalid_op+0x38/0x50 ? asm_exc_invalid_op+0x1a/0x20 ? iov_iter_revert+0x104/0x590 ? iov_iter_revert+0x41f/0x590 ? iov_iter_revert+0x420/0x590 netfs_reset_iter+0xce/0x130 netfs_read_subreq_terminated+0x1fe/0xad0 netfs_read_to_pagecache+0x628/0x900 netfs_readahead+0x7e9/0x9d0 ? __pfx_netfs_readahead+0x10/0x10 ? blk_start_plug+0x70/0x1b0 read_pages+0x180/0x840 ? __pfx_read_pages+0x10/0x10 ? filemap_add_folio+0x26d/0x650 ? __pfx_filemap_add_folio+0x10/0x10 ? rcu_read_lock_any_held+0xb7/0x160 ? __pfx_rcu_read_lock_any_held+0x10/0x10 ? __pfx_proc_fail_nth_write+0x10/0x10 page_cache_ra_unbounded+0x774/0x8a0 force_page_cache_ra+0x280/0x2f0 generic_fadvise+0x522/0x830 ? __pfx_generic_fadvise+0x10/0x10 ? lockdep_hardirqs_on_prepare+0x43d/0x780 ? __pfx_lockdep_hardirqs_on_prepare+0x10/0x10 ? vfs_fadvise+0x99/0xc0 __x64_sys_readahead+0x1ac/0x230 do_syscall_64+0xf3/0x230 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f2c116736a9 Code: 5c c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 4f 37 0d 00 f7 d8 64 89 01 48 RSP: 002b:00007ffc78181c88 EFLAGS: 00000246 ORIG_RAX: 00000000000000bb RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f2c116736a9 RDX: 000800000000000d RSI: 0000000000000005 RDI: 0000000000000006 RBP: 00000000004029d8 R08: 00007ffc78181658 R09: 00007f0038363735 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc78181cb0 R13: 00007ffc78181ec8 R14: 0000000000401120 R15: 00007f2c1178ca80 </TASK> This happens just because 'netfs_prepare_read_iterator()' may return -ENOMEM (which is actually triggered by the fault injection) but such a cases are not consistently handled in 'netfs_read_to_pagecache()'. So introduce 'netfs_wrap_read_iterator()' to handle all possible -ENOMEM cases and mark the corresponding subrequest as cancelled. Reported-by: syzbot+404b4b745080b6210c6c@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=404b4b745080b6210c6c Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading") Tested-by: syzbot+404b4b745080b6210c6c@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Dmitry Antipov <dmantipov@xxxxxxxxx> --- fs/netfs/buffered_read.c | 33 +++++++++++++++++++++++++++------ 1 file changed, 27 insertions(+), 6 deletions(-) diff --git a/fs/netfs/buffered_read.c b/fs/netfs/buffered_read.c index af46a598f4d7..706862094c49 100644 --- a/fs/netfs/buffered_read.c +++ b/fs/netfs/buffered_read.c @@ -174,6 +174,21 @@ static ssize_t netfs_prepare_read_iterator(struct netfs_io_subrequest *subreq) return subreq->len; } +/* Wrap the above by handling possible -ENOMEM and + * marking the corresponding subrequest as cancelled. + */ +static inline ssize_t netfs_wrap_read_iterator(struct netfs_io_subrequest *subreq) +{ + struct netfs_io_request *rreq = subreq->rreq; + ssize_t slice = netfs_prepare_read_iterator(subreq); + + if (unlikely(slice < 0)) { + atomic_dec(&rreq->nr_outstanding); + netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_cancel); + } + return slice; +} + static enum netfs_io_source netfs_cache_prepare_read(struct netfs_io_request *rreq, struct netfs_io_subrequest *subreq, loff_t i_size) @@ -284,10 +299,8 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq) trace_netfs_sreq(subreq, netfs_sreq_trace_prepare); } - slice = netfs_prepare_read_iterator(subreq); - if (slice < 0) { - atomic_dec(&rreq->nr_outstanding); - netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_cancel); + slice = netfs_wrap_read_iterator(subreq); + if (unlikely(slice < 0)) { ret = slice; break; } @@ -301,7 +314,11 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq) subreq->source = NETFS_FILL_WITH_ZEROES; trace_netfs_sreq(subreq, netfs_sreq_trace_submit); netfs_stat(&netfs_n_rh_zero); - slice = netfs_prepare_read_iterator(subreq); + slice = netfs_wrap_read_iterator(subreq); + if (unlikely(slice < 0)) { + ret = slice; + break; + } __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags); netfs_read_subreq_terminated(subreq, 0, false); goto done; @@ -309,7 +326,11 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq) if (source == NETFS_READ_FROM_CACHE) { trace_netfs_sreq(subreq, netfs_sreq_trace_submit); - slice = netfs_prepare_read_iterator(subreq); + slice = netfs_wrap_read_iterator(subreq); + if (unlikely(slice < 0)) { + ret = slice; + break; + } netfs_read_cache_to_pagecache(rreq, subreq); goto done; } -- 2.47.0
