5.15-stable review patch. If anyone has any objections, please let me know.
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From: Askar Safin safinaskar@zohomail.com
commit 042a60680de43175eb4df0977ff04a4eba9da082 upstream.
openat2 had a bug: if we pass RESOLVE_NO_XDEV, then openat2 doesn't traverse through automounts, but may still trigger them. (See the link for full bug report with reproducer.)
This commit fixes this bug.
Link: https://lore.kernel.org/linux-fsdevel/20250817075252.4137628-1-safinaskar@zo... Fixes: fddb5d430ad9fa91b49b1 ("open: introduce openat2(2) syscall") Reviewed-by: Aleksa Sarai cyphar@cyphar.com Cc: stable@vger.kernel.org Signed-off-by: Askar Safin safinaskar@zohomail.com Link: https://lore.kernel.org/20250825181233.2464822-5-safinaskar@zohomail.com Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/namei.c | 8 ++++++++ 1 file changed, 8 insertions(+)
--- a/fs/namei.c +++ b/fs/namei.c @@ -1307,6 +1307,10 @@ static int follow_automount(struct path dentry->d_inode) return -EISDIR;
+ /* No need to trigger automounts if mountpoint crossing is disabled. */ + if (lookup_flags & LOOKUP_NO_XDEV) + return -EXDEV; + if (count && (*count)++ >= MAXSYMLINKS) return -ELOOP;
@@ -1330,6 +1334,10 @@ static int __traverse_mounts(struct path /* Allow the filesystem to manage the transit without i_mutex * being held. */ if (flags & DCACHE_MANAGE_TRANSIT) { + if (lookup_flags & LOOKUP_NO_XDEV) { + ret = -EXDEV; + break; + } ret = path->dentry->d_op->d_manage(path, false); flags = smp_load_acquire(&path->dentry->d_flags); if (ret < 0)