From efe3de79e0b52ca281ef6691480c8c68c82a4657 Mon Sep 17 00:00:00 2001 From: Sachin Grover Date: Fri, 25 May 2018 14:01:39 +0530 Subject: [PATCH] selinux: KASAN: slab-out-of-bounds in xattr_getsecurity Call trace: [] dump_backtrace+0x0/0x428 [] show_stack+0x28/0x38 [] dump_stack+0xd4/0x124 [] print_address_description+0x68/0x258 [] kasan_report.part.2+0x228/0x2f0 [] kasan_report+0x5c/0x70 [] check_memory_region+0x12c/0x1c0 [] memcpy+0x34/0x68 [] xattr_getsecurity+0xe0/0x160 [] vfs_getxattr+0xc8/0x120 [] getxattr+0x100/0x2c8 [] SyS_fgetxattr+0x64/0xa0 [] el0_svc_naked+0x24/0x28 If user get root access and calls security.selinux setxattr() with an embedded NUL on a file and then if some process performs a getxattr() on that file with a length greater than the actual length of the string, it would result in a panic. To fix this, add the actual length of the string to the security context instead of the length passed by the userspace process. Signed-off-by: Sachin Grover Cc: stable@vger.kernel.org Signed-off-by: Paul Moore --- security/selinux/ss/services.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c index 8057e19dc15f..3ce225e3f142 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -1494,7 +1494,7 @@ static int security_context_to_sid_core(struct selinux_state *state, scontext_len, &context, def_sid); if (rc == -EINVAL && force) { context.str = str; - context.len = scontext_len; + context.len = strlen(str) + 1; str = NULL; } else if (rc) goto out_unlock;