* [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
end of thread, other threads:[~2025-10-21 8:47 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 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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