diff options
| author |   Qian Cai <cai@lca.pw> | 2020-09-10 08:26:15 -0700 |
|---|---|---|
| committer |   Darrick J. Wong <darrick.wong@oracle.com> | 2020-09-10 08:26:15 -0700 |
| commit | a805c111650cdba6ee880f528abdd03c1af82089 (patch) | |
| tree | fc7db90d60dccf7c13ec19455ec2fb0cc4031207 /fs/iomap | |
| parent | Linux 5.9-rc4 (diff) | |
| download | linux-dev-a805c111650cdba6ee880f528abdd03c1af82089.tar.xz linux-dev-a805c111650cdba6ee880f528abdd03c1af82089.zip | |
iomap: fix WARN_ON_ONCE() from unprivileged users
It is trivial to trigger a WARN_ON_ONCE(1) in iomap_dio_actor() by
unprivileged users which would taint the kernel, or worse - panic if
panic_on_warn or panic_on_taint is set. Hence, just convert it to
pr_warn_ratelimited() to let users know their workloads are racing.
Thank Dave Chinner for the initial analysis of the racing reproducers.
Signed-off-by: Qian Cai <cai@lca.pw>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/iomap')
| -rw-r--r-- | fs/iomap/direct-io.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index c1aafb2ab990..9519113ebc35 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -388,6 +388,16 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length, return iomap_dio_bio_actor(inode, pos, length, dio, iomap); case IOMAP_INLINE: return iomap_dio_inline_actor(inode, pos, length, dio, iomap); + case IOMAP_DELALLOC: + /* + * DIO is not serialised against mmap() access at all, and so + * if the page_mkwrite occurs between the writeback and the + * iomap_apply() call in the DIO path, then it will see the + * DELALLOC block that the page-mkwrite allocated. + */ + pr_warn_ratelimited("Direct I/O collision with buffered writes! File: %pD4 Comm: %.20s\n", + dio->iocb->ki_filp, current->comm); + return -EIO; default: WARN_ON_ONCE(1); return -EIO; |