Re: [PATCH v3 2/3] 9p: skip directory entries with names longer than NAME_MAX
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From: Christian Schoenebeck <linux_oss@crudebyte.com>
Date: 2026-09-18 11:09:32
Also in:
linux-fsdevel, lkml, v9fs
On Friday, 18 September 2026 04:48:50 CEST Haobin Wu wrote:
The 9p wire format carries directory entry names of up to 65535 bytes and nothing on the client checks them against NAME_MAX. Since the previous patch, v9fs_dir_readdir_dotl() passes such names straight to dir_emit(), and the VFS only rejects names of PATH_MAX bytes or more in verify_dirent_name(), as -EIO, which again fails the whole getdents64() call. A name between NAME_MAX and PATH_MAX is therefore returned to userspace even though every later operation on it fails with -ENAMETOOLONG, and POSIX requires readdir() to only return components of at most NAME_MAX bytes. Nothing can use such an entry, so skip it instead of returning it or failing the listing, reusing the strlen() result that was already computed for dir_emit(). Log the skipped entry at P9_DEBUG_ERROR, the same level as the strscpy() failure message this replaces. Suggested-by: Dominique Martinet <asmadeus@codewreck.org> Link: https://lore.kernel.org/all/vz5bum547fqyxf5z4m3x7tuqkuq52jlopm65t7hvynqeulh7i3@2t4wnhfxs7qv/ (local) Signed-off-by: Haobin Wu <redacted>
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
quoted hunk ↗ jump to hunk
--- fs/9p/vfs_dir.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)