* [PATCH 0/2] pipe: Fix a potential UAF and delete a duplicate line of code @ 2021-11-15 3:57 Zhen Lei 2021-11-15 3:57 ` [PATCH 1/2] pipe: fix potential use-after-free in pipe_read() Zhen Lei 2021-11-15 3:57 ` [PATCH 2/2] pipe: delete a duplicate line of code in pipe_write() Zhen Lei 0 siblings, 2 replies; 7+ messages in thread From: Zhen Lei @ 2021-11-15 3:57 UTC (permalink / raw) To: Alexander Viro, David Howells, linux-fsdevel, linux-kernel; +Cc: Zhen Lei I found these when I was learning the code. I briefly tested it, and no new problems were introduced. Zhen Lei (2): pipe: fix potential use-after-free in pipe_read() pipe: delete a duplicate line of code in pipe_write() fs/pipe.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) -- 2.26.0.106.g9fadedd ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH 1/2] pipe: fix potential use-after-free in pipe_read() 2021-11-15 3:57 [PATCH 0/2] pipe: Fix a potential UAF and delete a duplicate line of code Zhen Lei @ 2021-11-15 3:57 ` Zhen Lei 2021-11-15 4:25 ` Matthew Wilcox 2021-11-15 3:57 ` [PATCH 2/2] pipe: delete a duplicate line of code in pipe_write() Zhen Lei 1 sibling, 1 reply; 7+ messages in thread From: Zhen Lei @ 2021-11-15 3:57 UTC (permalink / raw) To: Alexander Viro, David Howells, linux-fsdevel, linux-kernel; +Cc: Zhen Lei Accessing buf->flags after pipe_buf_release(pipe, buf) is unsafe, because the 'buf' memory maybe freed. Fixes: e7d553d69cf6 ("pipe: Add notification lossage handling") Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> --- fs/pipe.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/pipe.c b/fs/pipe.c index 6d4342bad9f15b2..302f1e50ce3be1d 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -319,10 +319,12 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) } if (!buf->len) { + unsigned int __maybe_unused flags = buf->flags; + pipe_buf_release(pipe, buf); spin_lock_irq(&pipe->rd_wait.lock); #ifdef CONFIG_WATCH_QUEUE - if (buf->flags & PIPE_BUF_FLAG_LOSS) + if (flags & PIPE_BUF_FLAG_LOSS) pipe->note_loss = true; #endif tail++; -- 2.26.0.106.g9fadedd ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH 1/2] pipe: fix potential use-after-free in pipe_read() 2021-11-15 3:57 ` [PATCH 1/2] pipe: fix potential use-after-free in pipe_read() Zhen Lei @ 2021-11-15 4:25 ` Matthew Wilcox 2021-11-15 6:13 ` Leizhen (ThunderTown) 0 siblings, 1 reply; 7+ messages in thread From: Matthew Wilcox @ 2021-11-15 4:25 UTC (permalink / raw) To: Zhen Lei; +Cc: Alexander Viro, David Howells, linux-fsdevel, linux-kernel On Mon, Nov 15, 2021 at 11:57:20AM +0800, Zhen Lei wrote: > if (!buf->len) { > + unsigned int __maybe_unused flags = buf->flags; Why __maybe_unused? ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/2] pipe: fix potential use-after-free in pipe_read() 2021-11-15 4:25 ` Matthew Wilcox @ 2021-11-15 6:13 ` Leizhen (ThunderTown) 2021-11-15 13:05 ` Matthew Wilcox 0 siblings, 1 reply; 7+ messages in thread From: Leizhen (ThunderTown) @ 2021-11-15 6:13 UTC (permalink / raw) To: Matthew Wilcox; +Cc: Alexander Viro, David Howells, linux-fsdevel, linux-kernel On 2021/11/15 12:25, Matthew Wilcox wrote: > On Mon, Nov 15, 2021 at 11:57:20AM +0800, Zhen Lei wrote: >> if (!buf->len) { >> + unsigned int __maybe_unused flags = buf->flags; > > Why __maybe_unused? It's used only if "#ifdef CONFIG_WATCH_QUEUE". Otherwise, a warning will be reported. > . > ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/2] pipe: fix potential use-after-free in pipe_read() 2021-11-15 6:13 ` Leizhen (ThunderTown) @ 2021-11-15 13:05 ` Matthew Wilcox 2021-11-23 1:09 ` Leizhen (ThunderTown) 0 siblings, 1 reply; 7+ messages in thread From: Matthew Wilcox @ 2021-11-15 13:05 UTC (permalink / raw) To: Leizhen (ThunderTown) Cc: Alexander Viro, David Howells, linux-fsdevel, linux-kernel On Mon, Nov 15, 2021 at 02:13:44PM +0800, Leizhen (ThunderTown) wrote: > > > On 2021/11/15 12:25, Matthew Wilcox wrote: > > On Mon, Nov 15, 2021 at 11:57:20AM +0800, Zhen Lei wrote: > >> if (!buf->len) { > >> + unsigned int __maybe_unused flags = buf->flags; > > > > Why __maybe_unused? > > It's used only if "#ifdef CONFIG_WATCH_QUEUE". Otherwise, a warning will be reported. Better to turn the #ifdef into if (IS_ENABLED()) ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH 1/2] pipe: fix potential use-after-free in pipe_read() 2021-11-15 13:05 ` Matthew Wilcox @ 2021-11-23 1:09 ` Leizhen (ThunderTown) 0 siblings, 0 replies; 7+ messages in thread From: Leizhen (ThunderTown) @ 2021-11-23 1:09 UTC (permalink / raw) To: Matthew Wilcox; +Cc: Alexander Viro, David Howells, linux-fsdevel, linux-kernel On 2021/11/15 21:05, Matthew Wilcox wrote: > On Mon, Nov 15, 2021 at 02:13:44PM +0800, Leizhen (ThunderTown) wrote: >> >> >> On 2021/11/15 12:25, Matthew Wilcox wrote: >>> On Mon, Nov 15, 2021 at 11:57:20AM +0800, Zhen Lei wrote: >>>> if (!buf->len) { >>>> + unsigned int __maybe_unused flags = buf->flags; >>> >>> Why __maybe_unused? >> >> It's used only if "#ifdef CONFIG_WATCH_QUEUE". Otherwise, a warning will be reported. > > Better to turn the #ifdef into if (IS_ENABLED()) Hi, Matthew: Thank you for your advice. IS_ENABLED() is a good idea, but when I tried it, I found that the macro 'PIPE_BUF_FLAG_LOSS' and the structure member 'note_loss' were also separated by "ifdef CONFIG_WATCH_QUEUE", so this method is not suitable here. #ifdef CONFIG_WATCH_QUEUE #define PIPE_BUF_FLAG_LOSS 0x40 /* Message loss happened after this buffer */ #endif @@ -62,9 +60,7 @@ struct pipe_inode_info { unsigned int tail; unsigned int max_usage; unsigned int ring_size; #ifdef CONFIG_WATCH_QUEUE bool note_loss; #endif > . > ^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH 2/2] pipe: delete a duplicate line of code in pipe_write() 2021-11-15 3:57 [PATCH 0/2] pipe: Fix a potential UAF and delete a duplicate line of code Zhen Lei 2021-11-15 3:57 ` [PATCH 1/2] pipe: fix potential use-after-free in pipe_read() Zhen Lei @ 2021-11-15 3:57 ` Zhen Lei 1 sibling, 0 replies; 7+ messages in thread From: Zhen Lei @ 2021-11-15 3:57 UTC (permalink / raw) To: Alexander Viro, David Howells, linux-fsdevel, linux-kernel; +Cc: Zhen Lei The buf->offset has been assigned to 0 before the copy operation, and it seems odd to readjust its value after the copy is complete. Delete the second 'buf->offset = 0'. Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> --- fs/pipe.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/pipe.c b/fs/pipe.c index 302f1e50ce3be1d..7ba11a633c0eeb9 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -536,7 +536,6 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from) break; } ret += copied; - buf->offset = 0; buf->len = copied; if (!iov_iter_count(from)) -- 2.26.0.106.g9fadedd ^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2021-11-23 1:09 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-11-15 3:57 [PATCH 0/2] pipe: Fix a potential UAF and delete a duplicate line of code Zhen Lei 2021-11-15 3:57 ` [PATCH 1/2] pipe: fix potential use-after-free in pipe_read() Zhen Lei 2021-11-15 4:25 ` Matthew Wilcox 2021-11-15 6:13 ` Leizhen (ThunderTown) 2021-11-15 13:05 ` Matthew Wilcox 2021-11-23 1:09 ` Leizhen (ThunderTown) 2021-11-15 3:57 ` [PATCH 2/2] pipe: delete a duplicate line of code in pipe_write() Zhen Lei
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