6.5-stable review patch. If anyone has any objections, please let me know.
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From: Ondrej Mosnacek omosnace@redhat.com
commit b36995b8609a5a8fe5cf259a1ee768fcaed919f8 upstream.
-EOPNOTSUPP is the return value that implements a "no-op" hook, not 0.
Without this fix having only the BPF LSM enabled (with no programs attached) can cause uninitialized variable reads in nfsd4_encode_fattr(), because the BPF hook returns 0 without touching the 'ctxlen' variable and the corresponding 'contextlen' variable in nfsd4_encode_fattr() remains uninitialized, yet being treated as valid based on the 0 return value.
Cc: stable@vger.kernel.org Fixes: 98e828a0650f ("security: Refactor declaration of LSM hooks") Reported-by: Benjamin Coddington bcodding@redhat.com Signed-off-by: Ondrej Mosnacek omosnace@redhat.com Signed-off-by: Paul Moore paul@paul-moore.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/linux/lsm_hook_defs.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -273,7 +273,7 @@ LSM_HOOK(void, LSM_RET_VOID, release_sec LSM_HOOK(void, LSM_RET_VOID, inode_invalidate_secctx, struct inode *inode) LSM_HOOK(int, 0, inode_notifysecctx, struct inode *inode, void *ctx, u32 ctxlen) LSM_HOOK(int, 0, inode_setsecctx, struct dentry *dentry, void *ctx, u32 ctxlen) -LSM_HOOK(int, 0, inode_getsecctx, struct inode *inode, void **ctx, +LSM_HOOK(int, -EOPNOTSUPP, inode_getsecctx, struct inode *inode, void **ctx, u32 *ctxlen)
#if defined(CONFIG_SECURITY) && defined(CONFIG_WATCH_QUEUE)