Re: CVE-2021-47115: nfc: fix NULL ptr dereference in llcp_sock_getname() after failed connect

[Robert Frohl]

Hi all,

CVE-2021-47115 looks like a duplicate of CVE-2021-38208 [0].

Cheers,
Robert

[0] https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-38208


On 15.03.24 21:15, Greg Kroah-Hartman wrote:
> Description
> ===========
>
> In the Linux kernel, the following vulnerability has been resolved:
>
> nfc: fix NULL ptr dereference in llcp_sock_getname() after failed connect
>
> It's possible to trigger NULL pointer dereference by local unprivileged
> user, when calling getsockname() after failed bind() (e.g. the bind
> fails because LLCP_SAP_MAX used as SAP):
>
>    BUG: kernel NULL pointer dereference, address: 0000000000000000
>    CPU: 1 PID: 426 Comm: llcp_sock_getna Not tainted 5.13.0-rc2-next-20210521+ #9
>    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-1 04/01/2014
>    Call Trace:
>     llcp_sock_getname+0xb1/0xe0
>     __sys_getpeername+0x95/0xc0
>     ? lockdep_hardirqs_on_prepare+0xd5/0x180
>     ? syscall_enter_from_user_mode+0x1c/0x40
>     __x64_sys_getpeername+0x11/0x20
>     do_syscall_64+0x36/0x70
>     entry_SYSCALL_64_after_hwframe+0x44/0xae
>
> This can be reproduced with Syzkaller C repro (bind followed by
> getpeername):
> https://syzkaller.appspot.com/x/repro.c?x=14def446e00000
>
> The Linux kernel CVE team has assigned CVE-2021-47115 to this issue.
>
>
> Affected and fixed versions
> ===========================
>
> 	Issue introduced in 3.3 with commit d646960f7986 and fixed in 4.4.272 with commit eb6875d48590
> 	Issue introduced in 3.3 with commit d646960f7986 and fixed in 4.9.272 with commit 39c15bd2e5d1
> 	Issue introduced in 3.3 with commit d646960f7986 and fixed in 4.14.236 with commit ffff05b9ee5c
> 	Issue introduced in 3.3 with commit d646960f7986 and fixed in 4.19.194 with commit 93e4ac2a9979
> 	Issue introduced in 3.3 with commit d646960f7986 and fixed in 5.4.125 with commit 5d4c4b06ed9f
> 	Issue introduced in 3.3 with commit d646960f7986 and fixed in 5.10.43 with commit 48ee0db61c82
> 	Issue introduced in 3.3 with commit d646960f7986 and fixed in 5.12.10 with commit 0c4559736d9a
> 	Issue introduced in 3.3 with commit d646960f7986 and fixed in 5.13 with commit 4ac06a1e013c
>
> Please see https://www.kernel.org or a full list of currently supported
> kernel versions by the kernel community.
>
> Unaffected versions might change over time as fixes are backported to
> older supported kernel versions.  The official CVE entry at
> 	https://cve.org/CVERecord/?id=CVE-2021-47115
> will be updated if fixes are backported, please check that for the most
> up to date information about this issue.
>
>
> Affected files
> ==============
>
> The file(s) affected by this issue are:
> 	net/nfc/llcp_sock.c
>
>
> Mitigation
> ==========
>
> The Linux kernel CVE team recommends that you update to the latest
> stable kernel version for this, and many other bugfixes.  Individual
> changes are never tested alone, but rather are part of a larger kernel
> release.  Cherry-picking individual commits is not recommended or
> supported by the Linux kernel community at all.  If however, updating to
> the latest release is impossible, the individual changes to resolve this
> issue can be found at these commits:
> 	https://git.kernel.org/stable/c/eb6875d48590d8e564092e831ff07fa384d7e477
> 	https://git.kernel.org/stable/c/39c15bd2e5d11bcf7f4c3dba2aad9e1e110a5d94
> 	https://git.kernel.org/stable/c/ffff05b9ee5c74c04bba2801c1f99b31975d74d9
> 	https://git.kernel.org/stable/c/93e4ac2a9979a9a4ecc158409ed9c3044dc0ae1f
> 	https://git.kernel.org/stable/c/5d4c4b06ed9fb7a69d0b2e2a73fc73226d25ab70
> 	https://git.kernel.org/stable/c/48ee0db61c8299022ec88c79ad137f290196cac2
> 	https://git.kernel.org/stable/c/0c4559736d9a4ec1ca58ba98ca34e7c4da4c422b
> 	https://git.kernel.org/stable/c/4ac06a1e013cf5fdd963317ffd3b968560f33bba

--
Security Engineer, SUSE Software Solutions Germany GmbH, Frankenstraße 
146, 90461 Nürnberg, Germany, GF: Ivo Totev, Andrew McDonald, Werner 
Knoblich (HRB 36809, AG Nürnberg)
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