Bug 2351608 (CVE-2025-21855) - CVE-2025-21855 kernel: ibmvnic: Don't reference skb after sending to VIOS
Summary: CVE-2025-21855 kernel: ibmvnic: Don't reference skb after sending to VIOS
Keywords:
Status: NEW
Alias: CVE-2025-21855
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2025-03-12 12:23 UTC by OSIDB Bzimport
Modified: 2025-03-17 15:47 UTC (History)
4 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


Attachments (Terms of Use)

Description OSIDB Bzimport 2025-03-12 12:23:24 UTC
In the Linux kernel, the following vulnerability has been resolved:

ibmvnic: Don't reference skb after sending to VIOS

Previously, after successfully flushing the xmit buffer to VIOS,
the tx_bytes stat was incremented by the length of the skb.

It is invalid to access the skb memory after sending the buffer to
the VIOS because, at any point after sending, the VIOS can trigger
an interrupt to free this memory. A race between reading skb->len
and freeing the skb is possible (especially during LPM) and will
result in use-after-free:
 ==================================================================
 BUG: KASAN: slab-use-after-free in ibmvnic_xmit+0x75c/0x1808 [ibmvnic]
 Read of size 4 at addr c00000024eb48a70 by task hxecom/14495
 <...>
 Call Trace:
 [c000000118f66cf0] [c0000000018cba6c] dump_stack_lvl+0x84/0xe8 (unreliable)
 [c000000118f66d20] [c0000000006f0080] print_report+0x1a8/0x7f0
 [c000000118f66df0] [c0000000006f08f0] kasan_report+0x128/0x1f8
 [c000000118f66f00] [c0000000006f2868] __asan_load4+0xac/0xe0
 [c000000118f66f20] [c0080000046eac84] ibmvnic_xmit+0x75c/0x1808 [ibmvnic]
 [c000000118f67340] [c0000000014be168] dev_hard_start_xmit+0x150/0x358
 <...>
 Freed by task 0:
 kasan_save_stack+0x34/0x68
 kasan_save_track+0x2c/0x50
 kasan_save_free_info+0x64/0x108
 __kasan_mempool_poison_object+0x148/0x2d4
 napi_skb_cache_put+0x5c/0x194
 net_tx_action+0x154/0x5b8
 handle_softirqs+0x20c/0x60c
 do_softirq_own_stack+0x6c/0x88
 <...>
 The buggy address belongs to the object at c00000024eb48a00 which
  belongs to the cache skbuff_head_cache of size 224
==================================================================

Comment 1 Avinash Hanwate 2025-03-13 07:14:55 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025031214-CVE-2025-21855-2d67@gregkh/T


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