4.9-stable review patch. If anyone has any objections, please let me know.
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From: Sachin Grover sgrover@codeaurora.org
commit efe3de79e0b52ca281ef6691480c8c68c82a4657 upstream.
Call trace: [<ffffff9203a8d7a8>] dump_backtrace+0x0/0x428 [<ffffff9203a8dbf8>] show_stack+0x28/0x38 [<ffffff920409bfb8>] dump_stack+0xd4/0x124 [<ffffff9203d187e8>] print_address_description+0x68/0x258 [<ffffff9203d18c00>] kasan_report.part.2+0x228/0x2f0 [<ffffff9203d1927c>] kasan_report+0x5c/0x70 [<ffffff9203d1776c>] check_memory_region+0x12c/0x1c0 [<ffffff9203d17cdc>] memcpy+0x34/0x68 [<ffffff9203d75348>] xattr_getsecurity+0xe0/0x160 [<ffffff9203d75490>] vfs_getxattr+0xc8/0x120 [<ffffff9203d75d68>] getxattr+0x100/0x2c8 [<ffffff9203d76fb4>] SyS_fgetxattr+0x64/0xa0 [<ffffff9203a83f70>] 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 sgrover@codeaurora.org Cc: stable@vger.kernel.org Signed-off-by: Paul Moore paul@paul-moore.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- security/selinux/ss/services.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -1435,7 +1435,7 @@ static int security_context_to_sid_core( 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;