I noticed a similar problem with the tcon link leak on that (which Colin and Gustavo pointed out - thank you!) but also in another return statement, so updated the original patch of Ronnie's merging the fixes
https://git.samba.org/sfrench/cifs-2.6.git/?p=sfrench/cifs-2.6.git;a=commit;h=167bc5de08dc97695f9d5c7069c3e69f409ff80b Let me know if you see any problems with it. On Fri, Apr 20, 2018 at 8:19 AM, Gustavo A. R. Silva <[email protected]> wrote: > Free allocated memory for full_path and xid before return. > > Addresses-Coverity-ID: 1468029 ("Resource leak") > Fixes: 49162bfde140 ("cifs: do not allow creating sockets except with > SMB1 posix exensions") > Signed-off-by: Gustavo A. R. Silva <[email protected]> > --- > fs/cifs/dir.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c > index f0a759d..71e32d9 100644 > --- a/fs/cifs/dir.c > +++ b/fs/cifs/dir.c > @@ -684,8 +684,11 @@ int cifs_mknod(struct inode *inode, struct dentry > *direntry, umode_t mode, > goto mknod_out; > } > > - if (!S_ISCHR(mode) && !S_ISBLK(mode)) > + if (!S_ISCHR(mode) && !S_ISBLK(mode)) { > + kfree(full_path); > + free_xid(xid); > return -EPERM; > + } > > if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL)) > goto mknod_out; > -- > 2.7.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-cifs" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Thanks, Steve
From 167bc5de08dc97695f9d5c7069c3e69f409ff80b Mon Sep 17 00:00:00 2001 From: Steve French <[email protected]> Date: Fri, 20 Apr 2018 12:19:07 -0500 Subject: [PATCH 1/2] cifs: do not allow creating sockets except with SMB1 posix exensions RHBZ: 1453123 Since at least the 3.10 kernel and likely a lot earlier we have not been able to create unix domain sockets in a cifs share when mounted using the SFU mount option (except when mounted with the cifs unix extensions to Samba e.g.) Trying to create a socket, for example using the af_unix command from xfstests will cause : BUG: unable to handle kernel NULL pointer dereference at 00000000 00000040 Since no one uses or depends on being able to create unix domains sockets on a cifs share the easiest fix to stop this vulnerability is to simply not allow creation of any other special files than char or block devices when sfu is used. Added update to Ronnie's patch to handle a tcon link leak, and to address a buf leak noticed by Gustavo and Colin. CC: Gustavo A. R. Silva <[email protected]> CC: Colin Ian King <[email protected]> Reported-by: Eryu Guan <[email protected]> Signed-off-by: Ronnie Sahlberg <[email protected]> Signed-off-by: Steve French <[email protected]> Cc: [email protected] --- fs/cifs/dir.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c index 81ba6e0d88d8..925844343038 100644 --- a/fs/cifs/dir.c +++ b/fs/cifs/dir.c @@ -684,6 +684,9 @@ int cifs_mknod(struct inode *inode, struct dentry *direntry, umode_t mode, goto mknod_out; } + if (!S_ISCHR(mode) && !S_ISBLK(mode)) + goto mknod_out; + if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL)) goto mknod_out; @@ -692,10 +695,8 @@ int cifs_mknod(struct inode *inode, struct dentry *direntry, umode_t mode, buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL); if (buf == NULL) { - kfree(full_path); rc = -ENOMEM; - free_xid(xid); - return rc; + goto mknod_out; } if (backup_cred(cifs_sb)) @@ -742,7 +743,7 @@ int cifs_mknod(struct inode *inode, struct dentry *direntry, umode_t mode, pdev->minor = cpu_to_le64(MINOR(device_number)); rc = tcon->ses->server->ops->sync_write(xid, &fid, &io_parms, &bytes_written, iov, 1); - } /* else if (S_ISFIFO) */ + } tcon->ses->server->ops->close(xid, tcon, &fid); d_drop(direntry); -- 2.14.1
