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Fri, 01 Nov 2024 07:37:04 -0700 (PDT) Date: Fri, 01 Nov 2024 07:37:04 -0700 In-Reply-To: <67238110.050a0220.35b515.015e.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6724e790.050a0220.35b515.0172.GAE@google.com> Subject: Re: [syzbot] Re: kernel BUG in iov_iter_revert (2) From: syzbot To: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com. *** Subject: Re: kernel BUG in iov_iter_revert (2) Author: dmantipov@yandex.ru #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 6c52d4da1c742cd01a797a4d0a2d3c5a60dc9bfe 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; }