From: Samuel Page <sam@bynar.io> mainline inclusion from mainline-v7.0 commit 51a8de6c50bf947c8f534cd73da4c8f0a13e7bed category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/14444 CVE: CVE-2026-31694 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- fuse_add_dirent_to_cache() computes a serialized dirent size from the server-controlled namelen field and copies the dirent into a single page-cache page. The existing logic only checks whether the dirent fits in the remaining space of the current page and advances to a fresh page if not. It never checks whether the dirent itself exceeds PAGE_SIZE. As a result, a malicious FUSE server can return a dirent with namelen=4095, producing a serialized record size of 4120 bytes. On 4 KiB page systems this causes memcpy() to overflow the cache page by 24 bytes into the following kernel page. Reject dirents that cannot fit in a single page before copying them into the readdir cache. Fixes: 69e34551152a ("fuse: allow caching readdir") Cc: stable@vger.kernel.org # v6.16+ Assisted-by: Bynario AI Signed-off-by: Samuel Page <sam@bynar.io> Reported-by: Qi Tang <tpluszz77@gmail.com> Reported-by: Zijun Hu <nightu@northwestern.edu> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Link: https://patch.msgid.link/20260420090139.662772-1-mszeredi@redhat.com Signed-off-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Long Li <leo.lilong@huawei.com> --- fs/fuse/readdir.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c index f18632027d8b..00b2fc180bc7 100644 --- a/fs/fuse/readdir.c +++ b/fs/fuse/readdir.c @@ -41,6 +41,10 @@ static void fuse_add_dirent_to_cache(struct file *file, unsigned int offset; void *addr; + /* Dirent doesn't fit in readdir cache page? Skip caching. */ + if (reclen > PAGE_SIZE) + return; + spin_lock(&fi->rdc.lock); /* * Is cache already completed? Or this entry does not go at the end of -- 2.52.0