capabilities: fix potential memleak on error path from vfs_getxattr_alloc()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: capabilities: fix potential memleak on error path from vfs_getxattr_alloc() In cap_inode_getsecurity(), we will use vfs_getxattr_alloc() to complete the memory allocation of tmpbuf, if we have completed the memory allocation of tmpbuf, but failed to call handler->get(...), there will be a memleak in below logic: |-- ret = (int)vfs_getxattr_alloc(mnt_userns, ...) | /* ^^^ alloc for tmpbuf */ |-- value = krealloc(*xattr_value, error + 1, flags) | /* ^^^ alloc memory */ |-- error = handler->get(handler, ...) | /* error! */ |-- *xattr_value = value | /* xattr_value is &tmpbuf (memory leak!) */ So we will try to free(tmpbuf) after vfs_getxattr_alloc() fails to fix it. [PM: subject line and backtrace tweaks]

References

• https://git.kernel.org/stable/c/6bb00eb21c0fbf18e5d3538c9ff0cf63fd0ace85
• https://git.kernel.org/stable/c/90577bcc01c4188416a47269f8433f70502abe98
• https://git.kernel.org/stable/c/0c3e6288da650d1ec911a259c77bc2d88e498603
• https://git.kernel.org/stable/c/cdf01c807e974048c43c7fd3ca574f6086a57906
• https://git.kernel.org/stable/c/2de8eec8afb75792440b8900a01d52b8f6742fd1
• https://git.kernel.org/stable/c/7480aeff0093d8c54377553ec6b31110bea37b4d
• https://git.kernel.org/stable/c/8cf0a1bc12870d148ae830a4ba88cfdf0e879cee