Bug 2348560 (CVE-2025-21725)

Summary: CVE-2025-21725 kernel: smb: client: fix oops due to unset link speed
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
A vulnerability was found in the Linux kernel's Server Message Block (SMB) client implementation, specifically within the Common Internet File System (CIFS) module. The issue arises when the client attempts to process network interface information provided by the server, particularly the LinkSpeed parameter. If the server omits this parameter or provides an unexpected value, the client may attempt to perform a division operation with a zero value, leading to a divide-by-zero error and subsequent kernel crash. This misconfiguration on the server could lead to system failure.
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Last Closed: Type: ---
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2025-02-27 03:03:14 UTC
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: 0000000000000000 RBX: ffff88811230022c RCX: ffffffffc041bd99
RDX: 0000000000000000 RSI: 0000000000000567 RDI: ffff888112300228
RBP: ffff888112300218 R08: fffff52000302f5f R09: ffffed1022fa58ac
R10: ffff888117d2c566 R11: 00000000fffffffe R12: ffff888112300200
R13: 000000012a15343f R14: 0000000000000001 R15: ffff888113f2db58
FS: 00007fe27119e740(0000) GS:ffff888148600000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe2633c5000 CR3: 0000000124da0000 CR4: 0000000000750ef0
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: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000040000 RCX: 00007fe271288911
RDX: 0000000000040000 RSI: 00007fe2633c6000 RDI: 0000000000000003
RBP: 00007ffe87c07a00 R08: 0000000000000000 R09: 00007fe2713e6380
R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000040000
R13: 00007fe2633c6000 R14: 0000000000000003 R15: 0000000000000000
 </TASK>

Fix this by setting cifs_server_iface::speed to a sane value (1Gbps)
by default when link speed is unset.