2023-09-25 04:54:40

by Su Hui

Subject: [PATCH] cifs: avoid possible NULL dereference

smatch warn:
fs/smb/client/file.c:4910 cifs_oplock_break() warn:
variable dereferenced before check 'inode' (see line 4881)

If 'inode' is NULL, print some warning and return.

Signed-off-by: Su Hui <[email protected]>
---
fs/smb/client/file.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index 2108b3b40ce9..37eed057ded0 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -4878,6 +4878,12 @@ void cifs_oplock_break(struct work_struct *work)
struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
oplock_break);
struct inode *inode = d_inode(cfile->dentry);
+
+ if (!inode) {
+ cifs_dbg(FYI, "%s : failed to find inode\n", __func__);
+ return;
+ }
+
struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
struct cifsInodeInfo *cinode = CIFS_I(inode);
struct cifs_tcon *tcon;
@@ -4907,7 +4913,7 @@ void cifs_oplock_break(struct work_struct *work)
cinode->oplock = 0;
}

- if (inode && S_ISREG(inode->i_mode)) {
+ if (S_ISREG(inode->i_mode)) {
if (CIFS_CACHE_READ(cinode))
break_lease(inode, O_RDONLY);
else
--
2.30.2

2023-09-25 15:08:09

by Dan Carpenter

Subject: Re: [PATCH] cifs: avoid possible NULL dereference

On Mon, Sep 25, 2023 at 12:52:21PM +0800, Su Hui wrote:
> diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
> index 2108b3b40ce9..37eed057ded0 100644
> --- a/fs/smb/client/file.c
> +++ b/fs/smb/client/file.c
> @@ -4878,6 +4878,12 @@ void cifs_oplock_break(struct work_struct *work)
> struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
> oplock_break);
> struct inode *inode = d_inode(cfile->dentry);
> +
> + if (!inode) {
> + cifs_dbg(FYI, "%s : failed to find inode\n", __func__);
> + return;
> + }
> +

Are we allowing this in the middle of the declaration block these days?

> struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
> struct cifsInodeInfo *cinode = CIFS_I(inode);
> struct cifs_tcon *tcon;


regards,
dan carpenter

2023-09-26 01:21:11

by Su Hui

Subject: Re: [PATCH] cifs: avoid possible NULL dereference

On 2023/9/25 23:07, Dan Carpenter wrote:
> On Mon, Sep 25, 2023 at 12:52:21PM +0800, Su Hui wrote:
>> diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
>> index 2108b3b40ce9..37eed057ded0 100644
>> --- a/fs/smb/client/file.c
>> +++ b/fs/smb/client/file.c
>> @@ -4878,6 +4878,12 @@ void cifs_oplock_break(struct work_struct *work)
>> struct cifsFileInfo *cfile = container_of(work, struct cifsFileInfo,
>> oplock_break);
>> struct inode *inode = d_inode(cfile->dentry);
>> +
>> + if (!inode) {
>> + cifs_dbg(FYI, "%s : failed to find inode\n", __func__);
>> + return;
>> + }
>> +
> Are we allowing this in the middle of the declaration block these days?
Really sorry for this, I will modify it right now.
Thanks for your reminder!

Su Hui

>
>> struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
>> struct cifsInodeInfo *cinode = CIFS_I(inode);
>> struct cifs_tcon *tcon;
>
> regards,
> dan carpenter