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author | Pengcheng Yang <yangpc@wangsu.com> | 2020-06-04 16:51:30 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-17 11:13:23 +0200 |
commit | 2a6c63d04d89227ee45d0234c8059e2bccc15d73 (patch) | |
tree | 95a1189c809fbab75f6d050e758aa8a4c06aa521 /kernel | |
parent | 0cdddbc0c7b4f54da3651a6cc2b68b6abb8b1880 (diff) | |
download | linux-stable-2a6c63d04d89227ee45d0234c8059e2bccc15d73.tar.gz linux-stable-2a6c63d04d89227ee45d0234c8059e2bccc15d73.tar.bz2 linux-stable-2a6c63d04d89227ee45d0234c8059e2bccc15d73.zip |
kernel/relay.c: fix read_pos error when multiple readers
[ Upstream commit 341a7213e5c1ce274cc0f02270054905800ea660 ]
When reading, read_pos should start with bytes_consumed, not file->f_pos.
Because when there is more than one reader, the read_pos corresponding to
file->f_pos may have been consumed, which will cause the data that has
been consumed to be read and the bytes_consumed update error.
Signed-off-by: Pengcheng Yang <yangpc@wangsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jann Horn <jannh@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>e
Link: http://lkml.kernel.org/r/1579691175-28949-1-git-send-email-yangpc@wangsu.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Stable-dep-of: 43ec16f1450f ("relayfs: fix out-of-bounds access in relay_file_read")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/relay.c | 17 |
1 files changed, 7 insertions, 10 deletions
diff --git a/kernel/relay.c b/kernel/relay.c index b7aa7df43955..0f027e04b009 100644 --- a/kernel/relay.c +++ b/kernel/relay.c @@ -997,14 +997,14 @@ static void relay_file_read_consume(struct rchan_buf *buf, /* * relay_file_read_avail - boolean, are there unconsumed bytes available? */ -static int relay_file_read_avail(struct rchan_buf *buf, size_t read_pos) +static int relay_file_read_avail(struct rchan_buf *buf) { size_t subbuf_size = buf->chan->subbuf_size; size_t n_subbufs = buf->chan->n_subbufs; size_t produced = buf->subbufs_produced; size_t consumed = buf->subbufs_consumed; - relay_file_read_consume(buf, read_pos, 0); + relay_file_read_consume(buf, 0, 0); consumed = buf->subbufs_consumed; @@ -1065,23 +1065,20 @@ static size_t relay_file_read_subbuf_avail(size_t read_pos, /** * relay_file_read_start_pos - find the first available byte to read - * @read_pos: file read position * @buf: relay channel buffer * - * If the @read_pos is in the middle of padding, return the + * If the read_pos is in the middle of padding, return the * position of the first actually available byte, otherwise * return the original value. */ -static size_t relay_file_read_start_pos(size_t read_pos, - struct rchan_buf *buf) +static size_t relay_file_read_start_pos(struct rchan_buf *buf) { size_t read_subbuf, padding, padding_start, padding_end; size_t subbuf_size = buf->chan->subbuf_size; size_t n_subbufs = buf->chan->n_subbufs; size_t consumed = buf->subbufs_consumed % n_subbufs; + size_t read_pos = consumed * subbuf_size + buf->bytes_consumed; - if (!read_pos) - read_pos = consumed * subbuf_size + buf->bytes_consumed; read_subbuf = read_pos / subbuf_size; padding = buf->padding[read_subbuf]; padding_start = (read_subbuf + 1) * subbuf_size - padding; @@ -1137,10 +1134,10 @@ static ssize_t relay_file_read(struct file *filp, do { void *from; - if (!relay_file_read_avail(buf, *ppos)) + if (!relay_file_read_avail(buf)) break; - read_start = relay_file_read_start_pos(*ppos, buf); + read_start = relay_file_read_start_pos(buf); avail = relay_file_read_subbuf_avail(read_start, buf); if (!avail) break; |