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A durable fp is not bound to its original share, so a client can preserve a file from a short-path share and reconnect it on a long-path share, making strcmp() read past the PATH_MAX buffer - with a long enough share path this oopses the kernel, and on a mapped page it also gives a byte-equality oracle on adjacent heap (the reconnect succeeds exactly when the out-of-bounds string equals the requested name). A same-share variant with the durable fp at the share root reads 1 byte past the buffer (strlen(ab_pathname) == share->path_sz). Check the prefix before indexing: the path must be longer than share->path_sz and the next character must be '/'. The comparison for the valid case is unchanged. Fixes: c8efcc786146 ("ksmbd: add support for durable handles v1/v2") Reported-by: Dairui Zhang Assisted-by: LLM Cc: stable@vger.kernel.org Signed-off-by: Dairui Zhang --- fs/smb/server/vfs_cache.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/smb/server/vfs_cache.c b/fs/smb/server/vfs_cache.c index 293dab9..52e83cf 100644 --- a/fs/smb/server/vfs_cache.c +++ b/fs/smb/server/vfs_cache.c @@ -1714,9 +1714,13 @@ int ksmbd_validate_name_reconnect(struct ksmbd_share_config *share, return -EACCES; } - if (name && strcmp(&ab_pathname[share->path_sz + 1], name)) { - ksmbd_debug(SMB, "invalid name reconnect %s\n", name); - ret = -EINVAL; + if (name) { + if (strlen(ab_pathname) <= share->path_sz || + ab_pathname[share->path_sz] != '/' || + strcmp(&ab_pathname[share->path_sz + 1], name)) { + ksmbd_debug(SMB, "invalid name reconnect %s\n", name); + ret = -EINVAL; + } } kfree(pathname); -- 2.53.0