[EDT] [PATCH] devpts/inode.c : Fix Possible dentry NULL dereference

[EDT] [PATCH] devpts/inode.c : Fix Possible dentry NULL dereference

[Maninder Singh]

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EP-F6AA0618C49C4AEDA73BFF1B39950BAB

Hi,

Subject: [PATCH 1/1] devpts/inode.c : Fix Possible dentry NULL dereference

Issue reported by static tool Analyzer (Prevent).
d_find_alias can return NULL to deentry, Thus we need NULL check 
before calling d_delete(dentry)

Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Reviewed-by: Vaneet Narang <v.narang@samsung.com>
---
 fs/devpts/inode.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
index add5663..0350ac2 100644
--- a/fs/devpts/inode.c
+++ b/fs/devpts/inode.c
@@ -663,7 +663,8 @@ void devpts_pty_kill(struct inode *inode)
 	dentry = d_find_alias(inode);
 
 	drop_nlink(inode);
-	d_delete(dentry);
+	if (dentry)
+		d_delete(dentry);
 	dput(dentry);	/* d_alloc_name() in devpts_pty_new() */
 	dput(dentry);		/* d_find_alias above */
 
-- 
1.7.1

Thanks ,
Maninder Singhÿôèº{.nÇ+‰·Ÿ®‰­†+%ŠËÿ±éݶ\x17¥Šwÿº{.nÇ+‰·¥Š{±þG«éÿŠ{ayº\x1dʇڙë,j\a­¢f£¢·hšïêÿ‘êçz_è®\x03(­éšŽŠÝ¢j"ú\x1a¶^[m§ÿÿ¾\a«þG«éÿ¢¸?™¨è­Ú&£ø§~á¶iO•æ¬z·švØ^\x14\x04\x1a¶^[m§ÿÿÃ\fÿ¶ìÿ¢¸?–I¥

Re: [EDT] [PATCH] devpts/inode.c : Fix Possible dentry NULL dereference

[Richard Weinberger]

On Thu, May 21, 2015 at 12:28 PM, Maninder Singh
<maninder1.s@samsung.com> wrote:
>
> EP-F6AA0618C49C4AEDA73BFF1B39950BAB

What is this?

> Hi,
>
> Subject: [PATCH 1/1] devpts/inode.c : Fix Possible dentry NULL dereference
>
> Issue reported by static tool Analyzer (Prevent).
> d_find_alias can return NULL to deentry, Thus we need NULL check
> before calling d_delete(dentry)
>
> Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
> Reviewed-by: Vaneet Narang <v.narang@samsung.com>
> ---
>  fs/devpts/inode.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c
> index add5663..0350ac2 100644
> --- a/fs/devpts/inode.c
> +++ b/fs/devpts/inode.c
> @@ -663,7 +663,8 @@ void devpts_pty_kill(struct inode *inode)
>         dentry = d_find_alias(inode);
>
>         drop_nlink(inode);
> -       d_delete(dentry);
> +       if (dentry)
> +               d_delete(dentry);
>         dput(dentry);   /* d_alloc_name() in devpts_pty_new() */
>         dput(dentry);           /* d_find_alias above */

While it is correct that d_find_alias() may return NULL, can this also
happen here?
I mean if that happens in the kill path we might have bigger trouble...

Al?

-- 
Thanks,
//richard

Re: [EDT] [PATCH] devpts/inode.c : Fix Possible dentry NULL dereference

[Al Viro]

On Thu, May 21, 2015 at 10:28:52AM +0000, Maninder Singh wrote:

> Subject: [PATCH 1/1] devpts/inode.c : Fix Possible dentry NULL dereference
> 
> Issue reported by static tool Analyzer (Prevent).
> d_find_alias can return NULL to deentry, Thus we need NULL check 
> before calling d_delete(dentry)

No, we do not.  That inode must have come from devpts_pty_new() and it
wouldn't have made it out of there without having a dentry attached to
it (and pinned).

NAK.