ovl: fix memory leak in ovl_parse_param()
On failure to parse parameters in ovl_parse_param_lowerdir(), it is
necessary to update ctx->nr with the correct nr before using
ovl_reset_lowerdirs() to release l->name.
Reported-and-tested-by: syzbot+26eedf3631650972f17c@syzkaller.appspotmail.com
Fixes: c835110b588a ("ovl: remove unused code in lowerdir param parsing")
Co-authored-by: Edward Adam Davis <eadavis@qq.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index ddab9ea..3fe2dde 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -430,7 +430,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
struct ovl_fs_context *ctx = fc->fs_private;
struct ovl_fs_context_layer *l;
char *dup = NULL, *iter;
- ssize_t nr_lower = 0, nr = 0, nr_data = 0;
+ ssize_t nr_lower, nr;
bool data_layer = false;
/*
@@ -482,6 +482,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
iter = dup;
l = ctx->lower;
for (nr = 0; nr < nr_lower; nr++, l++) {
+ ctx->nr++;
memset(l, 0, sizeof(*l));
err = ovl_mount_dir(iter, &l->path);
@@ -498,10 +499,10 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
goto out_put;
if (data_layer)
- nr_data++;
+ ctx->nr_data++;
/* Calling strchr() again would overrun. */
- if ((nr + 1) == nr_lower)
+ if (ctx->nr == nr_lower)
break;
err = -EINVAL;
@@ -511,7 +512,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
* This is a regular layer so we require that
* there are no data layers.
*/
- if ((ctx->nr_data + nr_data) > 0) {
+ if (ctx->nr_data > 0) {
pr_err("regular lower layers cannot follow data lower layers");
goto out_put;
}
@@ -524,8 +525,6 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
data_layer = true;
iter++;
}
- ctx->nr = nr_lower;
- ctx->nr_data += nr_data;
kfree(dup);
return 0;
