From: David Disseldorp <ddiss@suse.de>
Date: Fri, 23 Apr 2021 00:14:03 +0200
Subject: [PATCH] cifs: fix leak in cifs_smb3_do_mount() ctx
Git-commit: 315db9a05b7a56810728589baa930864107e4634
Patch-mainline: v5.13-rc1
References: bsc#1192606
cifs_smb3_do_mount() calls smb3_fs_context_dup() and then
cifs_setup_volume_info(). The latter's subsequent smb3_parse_devname()
call overwrites the cifs_sb->ctx->UNC string already dup'ed by
smb3_fs_context_dup(), resulting in a leak. E.g.
unreferenced object 0xffff888002980420 (size 32):
comm "mount", pid 160, jiffies 4294892541 (age 30.416s)
hex dump (first 32 bytes):
5c 5c 31 39 32 2e 31 36 38 2e 31 37 34 2e 31 30 \\192.168.174.10
34 5c 72 61 70 69 64 6f 2d 73 68 61 72 65 00 00 4\rapido-share..
backtrace:
[<00000000069e12f6>] kstrdup+0x28/0x50
[<00000000b61f4032>] smb3_fs_context_dup+0x127/0x1d0 [cifs]
[<00000000c6e3e3bf>] cifs_smb3_do_mount+0x77/0x660 [cifs]
[<0000000063467a6b>] smb3_get_tree+0xdf/0x220 [cifs]
[<00000000716f731e>] vfs_get_tree+0x1b/0x90
[<00000000491d3892>] path_mount+0x62a/0x910
[<0000000046b2e774>] do_mount+0x50/0x70
[<00000000ca7b64dd>] __x64_sys_mount+0x81/0xd0
[<00000000b5122496>] do_syscall_64+0x33/0x40
[<000000002dd397af>] entry_SYSCALL_64_after_hwframe+0x44/0xae
This change is a bandaid until the cifs_setup_volume_info() TODO and
error handling issues are resolved.
Signed-off-by: David Disseldorp <ddiss@suse.de>
Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
CC: <stable@vger.kernel.org> # v5.11+
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
fs/cifs/cifsfs.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 4257f841ec4e..39f4889a036b 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -855,6 +855,12 @@ cifs_smb3_do_mount(struct file_system_type *fs_type,
goto out;
}
+ /* cifs_setup_volume_info->smb3_parse_devname() redups UNC & prepath */
+ kfree(cifs_sb->ctx->UNC);
+ cifs_sb->ctx->UNC = NULL;
+ kfree(cifs_sb->ctx->prepath);
+ cifs_sb->ctx->prepath = NULL;
+
rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, old_ctx->UNC);
if (rc) {
root = ERR_PTR(rc);
--
2.33.1