FAILED: patch "[PATCH] smb: client: fix memory leak in cifs_construct_tcon()" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 3184b6a5a24ec9ee74087b2a550476f386df7dc2
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025120143-confider-enzyme-4aa6@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 3184b6a5a24ec9ee74087b2a550476f386df7dc2 Mon Sep 17 00:00:00 2001
From: Paulo Alcantara <[email protected]>
Date: Mon, 24 Nov 2025 17:00:36 -0300
Subject: [PATCH] smb: client: fix memory leak in cifs_construct_tcon()

When having a multiuser mount with domain= specified and using cifscreds, cifs_set_cifscreds() will end up setting @ctx->domainname, so it needs to be freed before leaving cifs_construct_tcon().

This fixes the following memory leak reported by kmemleak:

mount.cifs //srv/share /mnt -o domain=ZELDA,multiuser,... su - testuser
cifscreds add -d ZELDA -u testuser
...
ls /mnt/1
...
umount /mnt
echo scan > /sys/kernel/debug/kmemleak
cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff8881203c3f08 (size 8):

    comm "ls", pid 5060, jiffies 4307222943
    hex dump (first 8 bytes):
      5a 45 4c 44 41 00 cc cc                          ZELDA...
    backtrace (crc d109a8cf):
      __kmalloc_node_track_caller_noprof+0x572/0x710
      kstrdup+0x3a/0x70
      cifs_sb_tlink+0x1209/0x1770 [cifs]
      cifs_get_fattr+0xe1/0xf50 [cifs]
      cifs_get_inode_info+0xb5/0x240 [cifs]
      cifs_revalidate_dentry_attr+0x2d1/0x470 [cifs]
      cifs_getattr+0x28e/0x450 [cifs]
      vfs_getattr_nosec+0x126/0x180
      vfs_statx+0xf6/0x220
      do_statx+0xab/0x110
      __x64_sys_statx+0xd5/0x130
      do_syscall_64+0xbb/0x380
      entry_SYSCALL_64_after_hwframe+0x77/0x7f

index 55cb4b0cbd48..2f94d93b95e9 100644
@@ -4451,6 +4451,7 @@ cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
 
 out:
 	kfree(ctx->username);
+	kfree(ctx->domainname);
 	kfree_sensitive(ctx->password);
 	kfree(origin_fullpath);
 	kfree(ctx);

From: Paulo Alcantara <[email protected]>

[ Upstream commit 3184b6a5a24ec9ee74087b2a550476f386df7dc2 ]

When having a multiuser mount with domain= specified and using cifscreds, cifs_set_cifscreds() will end up setting @ctx->domainname, so it needs to be freed before leaving cifs_construct_tcon().

This fixes the following memory leak reported by kmemleak:

mount.cifs //srv/share /mnt -o domain=ZELDA,multiuser,... su - testuser
cifscreds add -d ZELDA -u testuser
...
ls /mnt/1
...
umount /mnt
echo scan > /sys/kernel/debug/kmemleak
cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff8881203c3f08 (size 8):

    comm "ls", pid 5060, jiffies 4307222943
    hex dump (first 8 bytes):
      5a 45 4c 44 41 00 cc cc                          ZELDA...
    backtrace (crc d109a8cf):
      __kmalloc_node_track_caller_noprof+0x572/0x710
      kstrdup+0x3a/0x70
      cifs_sb_tlink+0x1209/0x1770 [cifs]
      cifs_get_fattr+0xe1/0xf50 [cifs]
      cifs_get_inode_info+0xb5/0x240 [cifs]
      cifs_revalidate_dentry_attr+0x2d1/0x470 [cifs]
      cifs_getattr+0x28e/0x450 [cifs]
      vfs_getattr_nosec+0x126/0x180
      vfs_statx+0xf6/0x220
      do_statx+0xab/0x110
      __x64_sys_statx+0xd5/0x130
      do_syscall_64+0xbb/0x380
      entry_SYSCALL_64_after_hwframe+0x77/0x7f

---
 fs/cifs/connect.c | 1 +
 1 file changed, 1 insertion(+)

index 51ceaf9ea3151..677c757fffffb 100644
@@ -3926,6 +3926,7 @@ cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
 
 out:
 	kfree(ctx->username);
+	kfree(ctx->domainname);
 	kfree_sensitive(ctx->password);
 	kfree(ctx);
 

2.51.0