* [PATCH] exfat: fix refcount leak in exfat_find
@ 2025-10-20 15:00 Shuhao Fu
2025-10-21 1:38 ` Yuezhang.Mo
0 siblings, 1 reply; 5+ messages in thread
From: Shuhao Fu @ 2025-10-20 15:00 UTC (permalink / raw)
To: Namjae Jeon, Sungjong Seo; +Cc: Yuezhang Mo, linux-fsdevel, linux-kernel
Fix refcount leaks in `exfat_find` related to `exfat_get_dentry_set`.
Function `exfat_get_dentry_set` would increase the reference counter of
`es->bh` on success. Therefore, `exfat_put_dentry_set` must be called
after `exfat_get_dentry_set` to ensure refcount consistency. In
`exfat_find`, two branchs fail to call `exfat_put_dentry_set`, leading
to possible resource leaks.
Fixes: 82ebecdc74ff ("exfat: fix improper check of dentry.stream.valid_size")
Fixes: 13940cef9549 ("exfat: add a check for invalid data size")
Signed-off-by: Shuhao Fu <sfual@cse.ust.hk>
---
fs/exfat/namei.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
index 745dce29d..083a9d790 100644
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -646,11 +646,13 @@ static int exfat_find(struct inode *dir, const struct qstr *qname,
info->size = le64_to_cpu(ep2->dentry.stream.size);
if (info->valid_size < 0) {
+ exfat_put_dentry_set(&es, false);
exfat_fs_error(sb, "data valid size is invalid(%lld)", info->valid_size);
return -EIO;
}
if (unlikely(EXFAT_B_TO_CLU_ROUND_UP(info->size, sbi) > sbi->used_clusters)) {
+ exfat_put_dentry_set(&es, false);
exfat_fs_error(sb, "data size is invalid(%lld)", info->size);
return -EIO;
}
--
2.39.5 (Apple Git-154)
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] exfat: fix refcount leak in exfat_find
2025-10-20 15:00 [PATCH] exfat: fix refcount leak in exfat_find Shuhao Fu
@ 2025-10-21 1:38 ` Yuezhang.Mo
2025-10-21 8:04 ` Shuhao Fu
0 siblings, 1 reply; 5+ messages in thread
From: Yuezhang.Mo @ 2025-10-21 1:38 UTC (permalink / raw)
To: Shuhao Fu, Namjae Jeon, Sungjong Seo
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
On Mon, Oct 20, 2025 23:00 Shuhao Fu <sfual@cse.ust.hk> wrote:
> Fix refcount leaks in `exfat_find` related to `exfat_get_dentry_set`.
>
> Function `exfat_get_dentry_set` would increase the reference counter of
> `es->bh` on success. Therefore, `exfat_put_dentry_set` must be called
> after `exfat_get_dentry_set` to ensure refcount consistency. In
> `exfat_find`, two branchs fail to call `exfat_put_dentry_set`, leading
> to possible resource leaks.
>
> Fixes: 82ebecdc74ff ("exfat: fix improper check of dentry.stream.valid_size")
> Fixes: 13940cef9549 ("exfat: add a check for invalid data size")
> Signed-off-by: Shuhao Fu <sfual@cse.ust.hk>
> ---
> fs/exfat/namei.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
> index 745dce29d..083a9d790 100644
> --- a/fs/exfat/namei.c
> +++ b/fs/exfat/namei.c
> @@ -646,11 +646,13 @@ static int exfat_find(struct inode *dir, const struct qstr *qname,
> info->size = le64_to_cpu(ep2->dentry.stream.size);
>
> if (info->valid_size < 0) {
> + exfat_put_dentry_set(&es, false);
> exfat_fs_error(sb, "data valid size is invalid(%lld)", info->valid_size);
> return -EIO;
> }
>
> if (unlikely(EXFAT_B_TO_CLU_ROUND_UP(info->size, sbi) > sbi->used_clusters)) {
> + exfat_put_dentry_set(&es, false);
> exfat_fs_error(sb, "data size is invalid(%lld)", info->size);
> return -EIO;
> }
Thanks for your patch.
I think it would be better to move these checks after exfat_put_dentry_set().
Because the following check will correct ->valid_size and ->size.
if (!is_valid_cluster(sbi, info->start_clu) && info->size) {
exfat_warn(sb, "start_clu is invalid cluster(0x%x)",
info->start_clu);
info->size = 0;
info->valid_size = 0;
}
> --
> 2.39.5 (Apple Git-154)
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] exfat: fix refcount leak in exfat_find
2025-10-21 1:38 ` Yuezhang.Mo
@ 2025-10-21 8:04 ` Shuhao Fu
2025-10-21 8:21 ` Yuezhang.Mo
0 siblings, 1 reply; 5+ messages in thread
From: Shuhao Fu @ 2025-10-21 8:04 UTC (permalink / raw)
To: Yuezhang.Mo@sony.com
Cc: Namjae Jeon, Sungjong Seo, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
On Tue, Oct 21, 2025 at 01:38:29AM +0000, Yuezhang.Mo@sony.com wrote:
> On Mon, Oct 20, 2025 23:00 Shuhao Fu <sfual@cse.ust.hk> wrote:
>
> I think it would be better to move these checks after exfat_put_dentry_set().
> Because the following check will correct ->valid_size and ->size.
>
> if (!is_valid_cluster(sbi, info->start_clu) && info->size) {
> exfat_warn(sb, "start_clu is invalid cluster(0x%x)",
> info->start_clu);
> info->size = 0;
> info->valid_size = 0;
> }
>
Do you mean that we should put these two checks after
`exfat_put_dentry_set`, like below?
@@ -645,18 +645,6 @@ static int exfat_find(struct inode *dir, const struct qstr *qname,
info->valid_size = le64_to_cpu(ep2->dentry.stream.valid_size);
info->size = le64_to_cpu(ep2->dentry.stream.size);
- if (info->valid_size < 0) {
- exfat_fs_error(sb, "data valid size is invalid(%lld)", info->valid_size);
- return -EIO;
- }
-
- if (unlikely(EXFAT_B_TO_CLU_ROUND_UP(info->size, sbi) > sbi->used_clusters)) {
- exfat_fs_error(sb, "data size is invalid(%lld)", info->size);
- return -EIO;
- }
-
info->start_clu = le32_to_cpu(ep2->dentry.stream.start_clu);
if (!is_valid_cluster(sbi, info->start_clu) && info->size) {
exfat_warn(sb, "start_clu is invalid cluster(0x%x)",
@@ -694,6 +682,16 @@ static int exfat_find(struct inode *dir, const struct qstr *qname,
0);
exfat_put_dentry_set(&es, false);
+ if (info->valid_size < 0) {
+ exfat_fs_error(sb, "data valid size is invalid(%lld)", info->valid_size);
+ return -EIO;
+ }
+
+ if (unlikely(EXFAT_B_TO_CLU_ROUND_UP(info->size, sbi) > sbi->used_clusters)) {
+ exfat_fs_error(sb, "data size is invalid(%lld)", info->size);
+ return -EIO;
+ }
+
if (ei->start_clu == EXFAT_FREE_CLUSTER) {
exfat_fs_error(sb,
"non-zero size file starts with zero cluster (size : %llu, p_dir : %u, entry : 0x%08x)",
> > --
> > 2.39.5 (Apple Git-154)
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] exfat: fix refcount leak in exfat_find
2025-10-21 8:04 ` Shuhao Fu
@ 2025-10-21 8:21 ` Yuezhang.Mo
2025-10-21 8:47 ` Shuhao Fu
0 siblings, 1 reply; 5+ messages in thread
From: Yuezhang.Mo @ 2025-10-21 8:21 UTC (permalink / raw)
To: Shuhao Fu
Cc: Namjae Jeon, Sungjong Seo, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
On Tue, Oct 21, 2025 16:04 Shuhao Fu <sfual@cse.ust.hk> wrote:
> On Tue, Oct 21, 2025 at 01:38:29AM +0000, Yuezhang.Mo@sony.com wrote:
> > On Mon, Oct 20, 2025 23:00 Shuhao Fu <sfual@cse.ust.hk> wrote:
> >
> > I think it would be better to move these checks after exfat_put_dentry_set().
> > Because the following check will correct ->valid_size and ->size.
> >
> > if (!is_valid_cluster(sbi, info->start_clu) && info->size) {
> > exfat_warn(sb, "start_clu is invalid cluster(0x%x)",
> > info->start_clu);
> > info->size = 0;
> > info->valid_size = 0;
> > }
> >
>
> Do you mean that we should put these two checks after
> `exfat_put_dentry_set`, like below?
>
Yes, that's what I mean.
> @@ -645,18 +645,6 @@ static int exfat_find(struct inode *dir, const struct qstr *qname,
> info->valid_size = le64_to_cpu(ep2->dentry.stream.valid_size);
> info->size = le64_to_cpu(ep2->dentry.stream.size);
>
> - if (info->valid_size < 0) {
> - exfat_fs_error(sb, "data valid size is invalid(%lld)", info->valid_size);
> - return -EIO;
> - }
> -
> - if (unlikely(EXFAT_B_TO_CLU_ROUND_UP(info->size, sbi) > sbi->used_clusters)) {
> - exfat_fs_error(sb, "data size is invalid(%lld)", info->size);
> - return -EIO;
> - }
> -
> info->start_clu = le32_to_cpu(ep2->dentry.stream.start_clu);
> if (!is_valid_cluster(sbi, info->start_clu) && info->size) {
> exfat_warn(sb, "start_clu is invalid cluster(0x%x)",
> @@ -694,6 +682,16 @@ static int exfat_find(struct inode *dir, const struct qstr *qname,
> 0);
> exfat_put_dentry_set(&es, false);
>
> + if (info->valid_size < 0) {
> + exfat_fs_error(sb, "data valid size is invalid(%lld)", info->valid_size);
> + return -EIO;
> + }
> +
> + if (unlikely(EXFAT_B_TO_CLU_ROUND_UP(info->size, sbi) > sbi->used_clusters)) {
> + exfat_fs_error(sb, "data size is invalid(%lld)", info->size);
> + return -EIO;
> + }
> +
> if (ei->start_clu == EXFAT_FREE_CLUSTER) {
> exfat_fs_error(sb,
> "non-zero size file starts with zero cluster (size : %llu, p_dir : %u, entry : 0x%08x)",
>
> > > --
> > > 2.39.5 (Apple Git-154)
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] exfat: fix refcount leak in exfat_find
2025-10-21 8:21 ` Yuezhang.Mo
@ 2025-10-21 8:47 ` Shuhao Fu
0 siblings, 0 replies; 5+ messages in thread
From: Shuhao Fu @ 2025-10-21 8:47 UTC (permalink / raw)
To: Yuezhang.Mo@sony.com
Cc: Namjae Jeon, Sungjong Seo, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
On Tue, Oct 21, 2025 at 08:21:57AM +0000, Yuezhang.Mo@sony.com wrote:
> On Tue, Oct 21, 2025 16:04 Shuhao Fu <sfual@cse.ust.hk> wrote:
> > On Tue, Oct 21, 2025 at 01:38:29AM +0000, Yuezhang.Mo@sony.com wrote:
> > > On Mon, Oct 20, 2025 23:00 Shuhao Fu <sfual@cse.ust.hk> wrote:
> > >
> > > I think it would be better to move these checks after exfat_put_dentry_set().
> > > Because the following check will correct ->valid_size and ->size.
> > >
> > > if (!is_valid_cluster(sbi, info->start_clu) && info->size) {
> > > exfat_warn(sb, "start_clu is invalid cluster(0x%x)",
> > > info->start_clu);
> > > info->size = 0;
> > > info->valid_size = 0;
> > > }
> > >
> >
> > Do you mean that we should put these two checks after
> > `exfat_put_dentry_set`, like below?
> >
>
> Yes, that's what I mean.
>
Thank you for your suggestion. Patch v2 has been sent out addressing
your comments.
https://lore.kernel.org/linux-fsdevel/aPdHWFiCupwDRiFM@osx.local/
^ permalink raw reply [flat|nested] 5+ messages in thread
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2025-10-20 15:00 [PATCH] exfat: fix refcount leak in exfat_find Shuhao Fu
2025-10-21 1:38 ` Yuezhang.Mo
2025-10-21 8:04 ` Shuhao Fu
2025-10-21 8:21 ` Yuezhang.Mo
2025-10-21 8:47 ` Shuhao Fu
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