6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
[ Upstream commit ca76ac36bb6068866feca185045e7edf2a8f392f ]
The max count of lowerdir is OVL_MAX_STACK[500], which is broken by
commit 37f32f526438("ovl: fix memory leak in ovl_parse_param()") for
parameter Opt_lowerdir. Since commit 819829f0319a("ovl: refactor layer
parsing helpers") and commit 24e16e385f22("ovl: add support for
appending lowerdirs one by one") added check ovl_mount_dir_check() in
function ovl_parse_param_lowerdir(), the 'ctx->nr' should be smaller
than OVL_MAX_STACK, after commit 37f32f526438("ovl: fix memory leak in
ovl_parse_param()") is applied, the 'ctx->nr' is updated before the
check ovl_mount_dir_check(), which leads the max count of lowerdir
to become 499 for parameter Opt_lowerdir.
Fix it by replacing lower layers parsing code with the existing helper
function ovl_parse_layer().
Fixes: 37f32f526438 ("ovl: fix memory leak in ovl_parse_param()")
Signed-off-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240705011510.794025-3-chengzhihao1@xxxxxxxxxx
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/overlayfs/params.c | 40 +++++++---------------------------------
1 file changed, 7 insertions(+), 33 deletions(-)
diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c
index 17b9c1838182d..39919a10ce1c9 100644
--- a/fs/overlayfs/params.c
+++ b/fs/overlayfs/params.c
@@ -357,6 +357,8 @@ static void ovl_add_layer(struct fs_context *fc, enum ovl_opt layer,
case Opt_datadir_add:
ctx->nr_data++;
fallthrough;
+ case Opt_lowerdir:
+ fallthrough;
case Opt_lowerdir_add:
WARN_ON(ctx->nr >= ctx->capacity);
l = &ctx->lower[ctx->nr++];
@@ -379,7 +381,7 @@ static int ovl_parse_layer(struct fs_context *fc, const char *layer_name, enum o
if (!name)
return -ENOMEM;
- if (upper)
+ if (upper || layer == Opt_lowerdir)
err = ovl_mount_dir(name, &path);
else
err = ovl_mount_dir_noesc(name, &path);
@@ -435,7 +437,6 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
{
int err;
struct ovl_fs_context *ctx = fc->fs_private;
- struct ovl_fs_context_layer *l;
char *dup = NULL, *iter;
ssize_t nr_lower, nr;
bool data_layer = false;
@@ -475,35 +476,11 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
goto out_err;
}
- if (nr_lower > ctx->capacity) {
- err = -ENOMEM;
- l = krealloc_array(ctx->lower, nr_lower, sizeof(*ctx->lower),
- GFP_KERNEL_ACCOUNT);
- if (!l)
- goto out_err;
-
- ctx->lower = l;
- ctx->capacity = nr_lower;
- }
-
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);
+ for (nr = 0; nr < nr_lower; nr++) {
+ err = ovl_parse_layer(fc, iter, Opt_lowerdir);
if (err)
- goto out_put;
-
- err = ovl_mount_dir_check(fc, &l->path, Opt_lowerdir, iter, false);
- if (err)
- goto out_put;
-
- err = -ENOMEM;
- l->name = kstrdup(iter, GFP_KERNEL_ACCOUNT);
- if (!l->name)
- goto out_put;
+ goto out_err;
if (data_layer)
ctx->nr_data++;
@@ -521,7 +498,7 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
*/
if (ctx->nr_data > 0) {
pr_err("regular lower layers cannot follow data lower layers");
- goto out_put;
+ goto out_err;
}
data_layer = false;
@@ -535,9 +512,6 @@ static int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc)
kfree(dup);
return 0;
-out_put:
- ovl_reset_lowerdirs(ctx);
-
out_err:
kfree(dup);
--
2.43.0
