CVE-2025-68219

In the Linux kernel, the following vulnerability has been resolved:

cifs: fix memory leak in smb3_fs_context_parse_param error path

Add proper cleanup of ctx->source and fc->source to the

cifs_parse_mount_err error handler. This ensures that memory allocated

for the source strings is correctly freed on all error paths, matching

the cleanup already performed in the success path by

smb3_cleanup_fs_context_contents().

Pointers are also set to NULL after freeing to prevent potential

double-free issues.

This change fixes a memory leak originally detected by syzbot. The

leak occurred when processing Opt_source mount options if an error

happened after ctx->source and fc->source were successfully

allocated but before the function completed.

The specific leak sequence was:

1. ctx->source = smb3_fs_context_fullpath(ctx, '/') allocates memory

2. fc->source = kstrdup(ctx->source, GFP_KERNEL) allocates more memory

3. A subsequent error jumps to cifs_parse_mount_err

4. The old error handler freed passwords but not the source strings,

causing the memory to leak.

This issue was not addressed by commit e8c73eb7db0a ("cifs: client:

fix memory leak in smb3_fs_context_parse_param"), which only fixed

leaks from repeated fsconfig() calls but not this error path.

Patch updated with minor change suggested by kernel test robot