@@ -95,7 +95,7 @@ static size_t netfs_load_buffer_from_ra(struct netfs_io_request *rreq,
}
/*
- * netfs_prepare_read_iterator - Prepare the subreq iterator for I/O
+ * __netfs_prepare_read_iterator - Prepare the subreq iterator for I/O
* @subreq: The subrequest to be set up
*
* Prepare the I/O iterator representing the read buffer on a subrequest for
@@ -109,7 +109,7 @@ static size_t netfs_load_buffer_from_ra(struct netfs_io_request *rreq,
* [!] NOTE: This must be run in the same thread as ->issue_read() was called
* in as we access the readahead_control struct.
*/
-static ssize_t netfs_prepare_read_iterator(struct netfs_io_subrequest *subreq)
+static ssize_t __netfs_prepare_read_iterator(struct netfs_io_subrequest *subreq)
{
struct netfs_io_request *rreq = subreq->rreq;
size_t rsize = subreq->len;
@@ -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_prepare_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)
@@ -285,9 +300,7 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq)
}
slice = netfs_prepare_read_iterator(subreq);
- if (slice < 0) {
- atomic_dec(&rreq->nr_outstanding);
- netfs_put_subrequest(subreq, false, netfs_sreq_trace_put_cancel);
+ if (unlikely(slice < 0)) {
ret = slice;
break;
}
@@ -302,6 +315,10 @@ static void netfs_read_to_pagecache(struct netfs_io_request *rreq)
trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
netfs_stat(&netfs_n_rh_zero);
slice = netfs_prepare_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;
@@ -310,6 +327,10 @@ 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);
+ if (unlikely(slice < 0)) {
+ ret = slice;
+ break;
+ }
netfs_read_cache_to_pagecache(rreq, subreq);
goto done;
}
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 wrap 'netfs_prepare_read_iterator()' to handle all possible -ENOMEM cases and mark the corresponding subrequest as cancelled. Reported-by: syzbot+404b4b745080b6210c6c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=404b4b745080b6210c6c Fixes: ee4cdf7ba857 ("netfs: Speed up buffered reading") Tested-by: syzbot+404b4b745080b6210c6c@syzkaller.appspotmail.com Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru> --- v2: adjusted to match 6.13.0-rc1 --- fs/netfs/buffered_read.c | 31 ++++++++++++++++++++++++++----- 1 file changed, 26 insertions(+), 5 deletions(-)