David Howells
e36bc9930d
[ Upstream commit378831e4da] Doing faccessat("/afs/some/directory", 0) triggers a BUG in the permissions check code. Fix this by just removing the BUG section. If no permissions are asked for, just return okay if the file exists. Also: (1) Split up the directory check so that it has separate if-statements rather than if-else-if (e.g. checking for MAY_EXEC shouldn't skip the check for MAY_READ and MAY_WRITE). (2) Check for MAY_CHDIR as MAY_EXEC. Without the main fix, the following BUG may occur: kernel BUG at fs/afs/security.c:386! invalid opcode: 0000 [#1] SMP PTI ... RIP: 0010:afs_permission+0x19d/0x1a0 [kafs] ... Call Trace: ? inode_permission+0xbe/0x180 ? do_faccessat+0xdc/0x270 ? do_syscall_64+0x60/0x1f0 ? entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes:00d3b7a453("[AFS]: Add security support.") Reported-by: Jonathan Billings <jsbillings@jsbillings.org> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.