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authorFedor Pchelkin <pchelkin@ispras.ru>2023-12-28 19:07:43 +0300
committerJohn Johansen <john.johansen@canonical.com>2024-01-04 01:35:39 -0800
commit55a8210c9e7d21ff2644809699765796d4bfb200 (patch)
tree88f48fddf075398f0925f07da7abb096b26e3c22 /security
parent1342ad786073e96fa813ad943c19f586157ae297 (diff)
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apparmor: avoid crash when parsed profile name is empty
When processing a packed profile in unpack_profile() described like "profile :ns::samba-dcerpcd /usr/lib*/samba/{,samba/}samba-dcerpcd {...}" a string ":samba-dcerpcd" is unpacked as a fully-qualified name and then passed to aa_splitn_fqname(). aa_splitn_fqname() treats ":samba-dcerpcd" as only containing a namespace. Thus it returns NULL for tmpname, meanwhile tmpns is non-NULL. Later aa_alloc_profile() crashes as the new profile name is NULL now. general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 6 PID: 1657 Comm: apparmor_parser Not tainted 6.7.0-rc2-dirty #16 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014 RIP: 0010:strlen+0x1e/0xa0 Call Trace: <TASK> ? strlen+0x1e/0xa0 aa_policy_init+0x1bb/0x230 aa_alloc_profile+0xb1/0x480 unpack_profile+0x3bc/0x4960 aa_unpack+0x309/0x15e0 aa_replace_profiles+0x213/0x33c0 policy_update+0x261/0x370 profile_replace+0x20e/0x2a0 vfs_write+0x2af/0xe00 ksys_write+0x126/0x250 do_syscall_64+0x46/0xf0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 </TASK> ---[ end trace 0000000000000000 ]--- RIP: 0010:strlen+0x1e/0xa0 It seems such behaviour of aa_splitn_fqname() is expected and checked in other places where it is called (e.g. aa_remove_profiles). Well, there is an explicit comment "a ns name without a following profile is allowed" inside. AFAICS, nothing can prevent unpacked "name" to be in form like ":samba-dcerpcd" - it is passed from userspace. Deny the whole profile set replacement in such case and inform user with EPROTO and an explaining message. Found by Linux Verification Center (linuxtesting.org). Fixes: 04dc715e24d0 ("apparmor: audit policy ns specified in policy load") Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru> Signed-off-by: John Johansen <john.johansen@canonical.com>
Diffstat (limited to 'security')
-rw-r--r--security/apparmor/policy_unpack.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c
index 9575da5fd4cb..dbf7d96257ad 100644
--- a/security/apparmor/policy_unpack.c
+++ b/security/apparmor/policy_unpack.c
@@ -832,6 +832,10 @@ static struct aa_profile *unpack_profile(struct aa_ext *e, char **ns_name)
tmpname = aa_splitn_fqname(name, strlen(name), &tmpns, &ns_len);
if (tmpns) {
+ if (!tmpname) {
+ info = "empty profile name";
+ goto fail;
+ }
*ns_name = kstrndup(tmpns, ns_len, GFP_KERNEL);
if (!*ns_name) {
info = "out of memory";