* [PATCH] Revert "ubifs: Fix memory leak bug in alloc_ubifs_info() error path"
@ 2019-10-24 8:25 Richard Weinberger
2019-11-15 13:21 ` Romain Izard
0 siblings, 1 reply; 3+ messages in thread
From: Richard Weinberger @ 2019-10-24 8:25 UTC (permalink / raw)
To: linux-mtd; +Cc: linux-fsdevel, Richard Weinberger, Wenwen Wang, linux-kernel
This reverts commit 9163e0184bd7d5f779934d34581843f699ad2ffd.
At the point when ubifs_fill_super() runs, we have already a reference
to the super block. So upon deactivate_locked_super() c will get
free()'ed via ->kill_sb().
Cc: Wenwen Wang <wenwen@cs.uga.edu>
Fixes: 9163e0184bd7 ("ubifs: Fix memory leak bug in alloc_ubifs_info() error path")
Reported-by: https://twitter.com/grsecurity/status/1180609139359277056
Signed-off-by: Richard Weinberger <richard@nod.at>
---
fs/ubifs/super.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 7d4547e5202d..5e1e8ec0589e 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -2267,10 +2267,8 @@ static struct dentry *ubifs_mount(struct file_system_type *fs_type, int flags,
}
} else {
err = ubifs_fill_super(sb, data, flags & SB_SILENT ? 1 : 0);
- if (err) {
- kfree(c);
+ if (err)
goto out_deact;
- }
/* We do not support atime */
sb->s_flags |= SB_ACTIVE;
if (IS_ENABLED(CONFIG_UBIFS_ATIME_SUPPORT))
--
2.16.4
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^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH] Revert "ubifs: Fix memory leak bug in alloc_ubifs_info() error path"
2019-10-24 8:25 [PATCH] Revert "ubifs: Fix memory leak bug in alloc_ubifs_info() error path" Richard Weinberger
@ 2019-11-15 13:21 ` Romain Izard
0 siblings, 0 replies; 3+ messages in thread
From: Romain Izard @ 2019-11-15 13:21 UTC (permalink / raw)
To: Richard Weinberger; +Cc: linux-fsdevel, Wenwen Wang, linux-mtd, linux-kernel
On Thu, Oct 24, 2019 at 10:25:35AM +0200, Richard Weinberger wrote:
> This reverts commit 9163e0184bd7d5f779934d34581843f699ad2ffd.
>
> At the point when ubifs_fill_super() runs, we have already a reference
> to the super block. So upon deactivate_locked_super() c will get
> free()'ed via ->kill_sb().
And without a revert, trying to mount a UBI volume with a squashfs image
on it as a UBIFS partition will lead to kernel panics due to the double
free.
>
> Cc: Wenwen Wang <wenwen@cs.uga.edu>
> Fixes: 9163e0184bd7 ("ubifs: Fix memory leak bug in alloc_ubifs_info() error path")
> Reported-by: https://twitter.com/grsecurity/status/1180609139359277056
> Signed-off-by: Richard Weinberger <richard@nod.at>
Tested-by: Romain Izard <romain.izard.pro@gmail.com>
> ---
> fs/ubifs/super.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
> index 7d4547e5202d..5e1e8ec0589e 100644
> --- a/fs/ubifs/super.c
> +++ b/fs/ubifs/super.c
> @@ -2267,10 +2267,8 @@ static struct dentry *ubifs_mount(struct file_system_type *fs_type, int flags,
> }
> } else {
> err = ubifs_fill_super(sb, data, flags & SB_SILENT ? 1 : 0);
> - if (err) {
> - kfree(c);
> + if (err)
> goto out_deact;
> - }
> /* We do not support atime */
> sb->s_flags |= SB_ACTIVE;
> if (IS_ENABLED(CONFIG_UBIFS_ATIME_SUPPORT))
> --
> 2.16.4
>
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^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH] Revert "ubifs: Fix memory leak bug in alloc_ubifs_info() error path"
@ 2019-10-30 14:52 Sascha Hauer
0 siblings, 0 replies; 3+ messages in thread
From: Sascha Hauer @ 2019-10-30 14:52 UTC (permalink / raw)
To: linux-mtd; +Cc: Richard Weinberger, Wenwen Wang, Sascha Hauer, kernel
This reverts commit 9163e0184bd7d5f779934d34581843f699ad2ffd.
There actually is no memory leak. After an sget() the ubifs info
structure will be freed in the kill_sb hook. Doing it again here
leads to a double free.
As this is non obvious leave a comment where c is freed.
Fixes: 9163e0184bd7 ("ubifs: Fix memory leak bug in alloc_ubifs_info() error path")
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
fs/ubifs/super.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 7d4547e5202d..ce1515d693a0 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -2267,10 +2267,9 @@ static struct dentry *ubifs_mount(struct file_system_type *fs_type, int flags,
}
} else {
err = ubifs_fill_super(sb, data, flags & SB_SILENT ? 1 : 0);
- if (err) {
- kfree(c);
+ if (err)
+ /* c will be freed in ubifs_fs_type.kill_sb */
goto out_deact;
- }
/* We do not support atime */
sb->s_flags |= SB_ACTIVE;
if (IS_ENABLED(CONFIG_UBIFS_ATIME_SUPPORT))
--
2.24.0.rc1
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^ permalink raw reply related [flat|nested] 3+ messages in thread
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2019-10-24 8:25 [PATCH] Revert "ubifs: Fix memory leak bug in alloc_ubifs_info() error path" Richard Weinberger
2019-11-15 13:21 ` Romain Izard
2019-10-30 14:52 Sascha Hauer
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