From: Eric Sandeen <sandeen@redhat.com> stable inclusion from stable-v6.6.87 commit 6dafa27764183738dc5368b669b71e3d0d154f12 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IC1QS8 CVE: CVE-2025-23138 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit f13abc1e8e1a3b7455511c4e122750127f6bc9b0 ] Currently, watch_queue_set_size() modifies the pipe buffers charged to user->pipe_bufs without updating the pipe->nr_accounted on the pipe itself, due to the if (!pipe_has_watch_queue()) test in pipe_resize_ring(). This means that when the pipe is ultimately freed, we decrement user->pipe_bufs by something other than what than we had charged to it, potentially leading to an underflow. This in turn can cause subsequent too_many_pipe_buffers_soft() tests to fail with -EPERM. To remedy this, explicitly account for the pipe usage in watch_queue_set_size() to match the number set via account_pipe_buffers() (It's unclear why watch_queue_set_size() does not update nr_accounted; it may be due to intentional overprovisioning in watch_queue_set_size()?) Fixes: e95aada4cb93d ("pipe: wakeup wr_wait after setting max_usage") Signed-off-by: Eric Sandeen <sandeen@redhat.com> Link: https://lore.kernel.org/r/206682a8-0604-49e5-8224-fdbe0c12b460@redhat.com Signed-off-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Yin Tirui <yintirui@huawei.com> Reviewed-by: Weilong Chen <chenweilong@huawei.com> --- kernel/watch_queue.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c index 778b4056700f..17254597accd 100644 --- a/kernel/watch_queue.c +++ b/kernel/watch_queue.c @@ -269,6 +269,15 @@ long watch_queue_set_size(struct pipe_inode_info *pipe, unsigned int nr_notes) if (ret < 0) goto error; + /* + * pipe_resize_ring() does not update nr_accounted for watch_queue + * pipes, because the above vastly overprovisions. Set nr_accounted on + * and max_usage this pipe to the number that was actually charged to + * the user above via account_pipe_buffers. + */ + pipe->max_usage = nr_pages; + pipe->nr_accounted = nr_pages; + ret = -ENOMEM; pages = kcalloc(sizeof(struct page *), nr_pages, GFP_KERNEL); if (!pages) -- 2.22.0