[PATCH 05/14] getcwd(2): saner logics around prepend_path() call
From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2021-05-19 00:51:14
Also in:
linux-fsdevel, linux-s390, lkml
Subsystem:
filesystems (vfs and infrastructure), the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
The only negative value that might get returned by prepend_path() is -ENAMETOOLONG, and that happens only on overflow. The same goes for prepend_unreachable(). Overflow is detectable by observing negative buflen, so we can simplify the control flow around the prepend_path() call. Expand prepend_unreachable(), while we are at it - that's the only caller. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> --- fs/d_path.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-)
diff --git a/fs/d_path.c b/fs/d_path.c
index 7f3fac544bbb..311d43287572 100644
--- a/fs/d_path.c
+++ b/fs/d_path.c@@ -211,11 +211,6 @@ char *d_absolute_path(const struct path *path, return res; } -static int prepend_unreachable(char **buffer, int *buflen) -{ - return prepend(buffer, buflen, "(unreachable)", 13); -} - static void get_fs_root_rcu(struct fs_struct *fs, struct path *root) { unsigned seq;
@@ -414,17 +409,13 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) int buflen = PATH_MAX; prepend(&cwd, &buflen, "", 1); - error = prepend_path(&pwd, &root, &cwd, &buflen); + if (prepend_path(&pwd, &root, &cwd, &buflen) > 0) + prepend(&cwd, &buflen, "(unreachable)", 13); rcu_read_unlock(); - if (error < 0) + if (buflen < 0) { + error = -ENAMETOOLONG; goto out; - - /* Unreachable from current root */ - if (error > 0) { - error = prepend_unreachable(&cwd, &buflen); - if (error) - goto out; } error = -ERANGE;
--
2.11.0