CVE: CVE-2025-21725
Published: 2025-02-27
Description: In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix oops due to unset link speed

It isn't guaranteed that NETWORK_INTERFACE_INFO::LinkSpeed will always
be set by the server, so the client must handle any values and then
prevent oopses like below from happening:

Oops: divide error: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 1323 Comm: cat Not tainted 6.13.0-rc7 #2
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-3.fc41
04/01/2014
RIP: 0010:cifs_debug_data_proc_show+0xa45/0x1460 [cifs] Code: 00 00 48
89 df e8 3b cd 1b c1 41 f6 44 24 2c 04 0f 84 50 01 00 00 48 89 ef e8
e7 d0 1b c1 49 8b 44 24 18 31 d2 49 8d 7c 24 28 <48> f7 74 24 18 48 89
c3 e8 6e cf 1b c1 41 8b 6c 24 28 49 8d 7c 24
RSP: 0018:ffffc90001817be0 EFLAGS: 00010246
RAX: [PII_REDACTED] RBX: ffff[PII_REDACTED]2c RCX: ffffffffc041bd99
RDX: [PII_REDACTED] RSI: [PII_REDACTED] RDI: ffff[PII_REDACTED]28
RBP: ffff[PII_REDACTED]18 R08: fffff52000302f5f R09: ffffed1022fa58ac
R10: ffff888117d2c566 R11: 00000000fffffffe R12: ffff[PII_REDACTED]00
R13: 000000012a15343f R14: [PII_REDACTED] R15: ffff888113f2db58
FS: 00007fe27119e740(0000) GS:ffff[PII_REDACTED]00(0000)
knlGS:[PII_REDACTED]
CS: 0010 DS: 0000 ES: 0000 CR0: [PII_REDACTED]
CR2: 00007fe2633c5000 CR3:[PII_REDACTED]da0000 CR4:[PII_REDACTED]750ef0
PKRU: 55555554
Call Trace:
 <TASK>
 ? __die_body.cold+0x19/0x27
 ? die+0x2e/0x50
 ? do_trap+0x159/0x1b0
 ? cifs_debug_data_proc_show+0xa45/0x1460 [cifs]
 ? do_error_trap+0x90/0x130
 ? cifs_debug_data_proc_show+0xa45/0x1460 [cifs]
 ? exc_divide_error+0x39/0x50
 ? cifs_debug_data_proc_show+0xa45/0x1460 [cifs]
 ? asm_exc_divide_error+0x1a/0x20
 ? cifs_debug_data_proc_show+0xa39/0x1460 [cifs]
 ? cifs_debug_data_proc_show+0xa45/0x1460 [cifs]
 ? seq_read_iter+0x42e/0x790
 seq_read_iter+0x19a/0x790
 proc_reg_read_iter+0xbe/0x110
 ? __pfx_proc_reg_read_iter+0x10/0x10
 vfs_read+0x469/0x570
 ? do_user_addr_fault+0x398/0x760
 ? __pfx_vfs_read+0x10/0x10
 ? find_held_lock+0x8a/0xa0
 ? __pfx_lock_release+0x10/0x10
 ksys_read+0xd3/0x170
 ? __pfx_ksys_read+0x10/0x10
 ? __rcu_read_unlock+0x50/0x270
 ? mark_held_locks+0x1a/0x90
 do_syscall_64+0xbb/0x1d0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe271288911
Code: 00 48 8b 15 01 25 10 00 f7 d8 64 89 02 b8 ff ff ff ff eb bd e8
20 ad 01 00 f3 0f 1e fa 80 3d b5 a7 10 00 00 74 13 31 c0 0f 05 <48> 3d
00 f0 ff ff 77 4f c3 66 0f 1f 44 00 00 55 48 89 e5 48 83 ec
RSP: 002b:00007ffe87c079d8 EFLAGS: 00000246 ORIG_RAX: [PII_REDACTED]
RAX: ffffffffffffffda RBX: [PII_REDACTED] RCX: 00007fe271288911
RDX: [PII_REDACTED] RSI: 00007fe2633c6000 RDI: [PII_REDACTED]
RBP: 00007ffe87c07a00 R08: [PII_REDACTED] R09: 00007fe2713e6380
R10: [PII_REDACTED] R11: [PII_REDACTED] R12: [PII_REDACTED]
R13: 00007fe2633c6000 R14: [PII_REDACTED] R15: [PII_REDACTED]
 </TASK>

Fix this by setting cifs_server_iface::speed to a sane value (1Gbps)
by default when link speed is unset.
CVSS Score: 5.5 (MEDIUM)
References: https://git.kernel.org/stable/c/208e102a2fca44e40a6c3f7b9e2609cfd17a15aa; https://git.kernel.org/stable/c/3f901c35e1a1b3ed1b528a17ffdb941aa0294458; https://git.kernel.org/stable/c/699179dfc8d7da457b152ca5d18ae45f9ed9beaa