Bug 1227808 (CVE-2024-40954)

Summary: VUL-0: CVE-2024-40954: kernel: net: do not leave a dangling sk pointer, when socket creation fails
Product: [Novell Products] SUSE Security Incidents Reporter: SMASH SMASH <smash_bz>
Component: IncidentsAssignee: Kernel Bugs <kernel-bugs>
Status: NEW --- QA Contact: Security Team bot <security-team>
Severity: Normal    
Priority: P3 - Medium CC: gianluca.gabrielli
Version: unspecified   
Target Milestone: ---   
Hardware: Other   
OS: Other   
URL: https://smash.suse.de/issue/413881/
Whiteboard:
Found By: Security Response Team Services Priority:
Business Priority: Blocker: ---
Marketing QA Status: --- IT Deployment: ---

Description SMASH SMASH 2024-07-15 13:15:23 UTC
In the Linux kernel, the following vulnerability has been resolved:

net: do not leave a dangling sk pointer, when socket creation fails

It is possible to trigger a use-after-free by:
  * attaching an fentry probe to __sock_release() and the probe calling the
    bpf_get_socket_cookie() helper
  * running traceroute -I 1.1.1.1 on a freshly booted VM

A KASAN enabled kernel will log something like below (decoded and stripped):
==================================================================
BUG: KASAN: slab-use-after-free in __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
Read of size 8 at addr ffff888007110dd8 by task traceroute/299

CPU: 2 PID: 299 Comm: traceroute Tainted: G            E      6.10.0-rc2+ #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
dump_stack_lvl (lib/dump_stack.c:117 (discriminator 1))
print_report (mm/kasan/report.c:378 mm/kasan/report.c:488)
? __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
kasan_report (mm/kasan/report.c:603)
? __sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
kasan_check_range (mm/kasan/generic.c:183 mm/kasan/generic.c:189)
__sock_gen_cookie (./arch/x86/include/asm/atomic64_64.h:15 ./include/linux/atomic/atomic-arch-fallback.h:2583 ./include/linux/atomic/atomic-instrumented.h:1611 net/core/sock_diag.c:29)
bpf_get_socket_ptr_cookie (./arch/x86/include/asm/preempt.h:94 ./include/linux/sock_diag.h:42 net/core/filter.c:5094 net/core/filter.c:5092)
bpf_prog_875642cf11f1d139___sock_release+0x6e/0x8e
bpf_trampoline_6442506592+0x47/0xaf
__sock_release (net/socket.c:652)
__sock_create (net/socket.c:1601)
...
Allocated by task 299 on cpu 2 at 78.328492s:
kasan_save_stack (mm/kasan/common.c:48)
kasan_save_track (mm/kasan/common.c:68)
__kasan_slab_alloc (mm/kasan/common.c:312 mm/kasan/common.c:338)
kmem_cache_alloc_noprof (mm/slub.c:3941 mm/slub.c:4000 mm/slub.c:4007)
sk_prot_alloc (net/core/sock.c:2075)
sk_alloc (net/core/sock.c:2134)
inet_create (net/ipv4/af_inet.c:327 net/ipv4/af_inet.c:252)
__sock_create (net/socket.c:1572)
__sys_socket (net/socket.c:1660 net/socket.c:1644 net/socket.c:1706)
__x64_sys_socket (net/socket.c:1718)
do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

Freed by task 299 on cpu 2 at 78.328502s:
kasan_save_stack (mm/kasan/common.c:48)
kasan_save_track (mm/kasan/common.c:68)
kasan_save_free_info (mm/kasan/generic.c:582)
poison_slab_object (mm/kasan/common.c:242)
__kasan_slab_free (mm/kasan/common.c:256)
kmem_cache_free (mm/slub.c:4437 mm/slub.c:4511)
__sk_destruct (net/core/sock.c:2117 net/core/sock.c:2208)
inet_create (net/ipv4/af_inet.c:397 net/ipv4/af_inet.c:252)
__sock_create (net/socket.c:1572)
__sys_socket (net/socket.c:1660 net/socket.c:1644 net/socket.c:1706)
__x64_sys_socket (net/socket.c:1718)
do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

Fix this by clearing the struct socket reference in sk_common_release() to cover
all protocol families create functions, which may already attached the
reference to the sk object with sock_init_data().

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2024-40954
https://www.cve.org/CVERecord?id=CVE-2024-40954
https://git.kernel.org/stable/c/454c454ed645fed051216b79622f7cb69c1638f5
https://git.kernel.org/stable/c/5dfe2408fd7dc4d2e7ac38a116ff0a37b1cfd3b9
https://git.kernel.org/stable/c/6cd4a78d962bebbaf8beb7d2ead3f34120e3f7b2
https://git.kernel.org/stable/c/78e4aa528a7b1204219d808310524344f627d069
https://git.kernel.org/stable/c/893eeba94c40d513cd0fe6539330ebdaea208c0e
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2024/CVE-2024-40954.mbox