From 55d6732b8015705a657d96fc5bd37fbed349624a Mon Sep 17 00:00:00 2001 From: Haobin Wu <853555@gmail.com> Date: Fri, 18 Sep 2026 10:48:51 +0800 Subject: [PATCH] 9p: skip over-long directory entry names for legacy 9p2000 too The legacy 9p2000 and 9p2000.u readdir path, v9fs_dir_readdir(), parses each entry with p9stat_read() and, unlike the 9p2000.L path, never had a 256-byte name limit: a name of any length up to the wire maximum was handed to dir_emit(). getdents64() therefore returned names longer than NAME_MAX that no later syscall can use, and failed with -EIO for names of PATH_MAX bytes or more. Apply the same NAME_MAX check as the previous patch does for v9fs_dir_readdir_dotl(), so both protocol variants behave the same. Note that this is a behaviour change for 9p2000 and 9p2000.u, Name length 256..4095: - before: listed, but unusable (ENAMETOOLONG) - now: entry skipped, fetch continues Name length >=4096: - before: aborts the entire fetch (similar to 9p2000.L side) - now: entry skipped, fetch continues Suggested-by: Christian Schoenebeck Link: https://lore.kernel.org/all/3910569.MHq7AAxBmi@weasel/ Signed-off-by: Haobin Wu <853555@gmail.com> Message-ID: <20260918024851.51229-4-853555@gmail.com> Signed-off-by: Dominique Martinet --- fs/9p/vfs_dir.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/fs/9p/vfs_dir.c b/fs/9p/vfs_dir.c index 6723550f62fd..b561f4ce020e 100644 --- a/fs/9p/vfs_dir.c +++ b/fs/9p/vfs_dir.c @@ -85,7 +85,6 @@ static struct p9_rdir *v9fs_alloc_rdir_buf(struct file *filp, int buflen) static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx) { - bool over; struct p9_wstat st; int err = 0; struct p9_fid *fid; @@ -125,6 +124,9 @@ static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx) rdir->offset = ctx->pos; } while (rdir->head < rdir->tail) { + bool over = false; + size_t namelen; + err = p9stat_read(fid->clnt, rdir->buf + rdir->head, rdir->tail - rdir->head, &st); if (err <= 0) { @@ -132,8 +134,15 @@ static int v9fs_dir_readdir(struct file *file, struct dir_context *ctx) return -EIO; } - over = !dir_emit(ctx, st.name, strlen(st.name), - QID2INO(&st.qid), dt_type(&st)); + namelen = strlen(st.name); + if (namelen > NAME_MAX) { + p9_debug(P9_DEBUG_ERROR, + "skip dentry: name length %zu > NAME_MAX\n", + namelen); + } else { + over = !dir_emit(ctx, st.name, namelen, + QID2INO(&st.qid), dt_type(&st)); + } p9stat_free(&st); if (over) return 0;