CVE-2025-38185
Analyzed Analyzed - Analysis Complete
BaseFortify

Publication date: 2025-07-04

Last updated on: 2025-12-18

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: atm: atmtcp: Free invalid length skb in atmtcp_c_send(). syzbot reported the splat below. [0] vcc_sendmsg() copies data passed from userspace to skb and passes it to vcc->dev->ops->send(). atmtcp_c_send() accesses skb->data as struct atmtcp_hdr after checking if skb->len is 0, but it's not enough. Also, when skb->len == 0, skb and sk (vcc) were leaked because dev_kfree_skb() is not called and sk_wmem_alloc adjustment is missing to revert atm_account_tx() in vcc_sendmsg(), which is expected to be done in atm_pop_raw(). Let's properly free skb with an invalid length in atmtcp_c_send(). [0]: BUG: KMSAN: uninit-value in atmtcp_c_send+0x255/0xed0 drivers/atm/atmtcp.c:294 atmtcp_c_send+0x255/0xed0 drivers/atm/atmtcp.c:294 vcc_sendmsg+0xd7c/0xff0 net/atm/common.c:644 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x330/0x3d0 net/socket.c:727 ____sys_sendmsg+0x7e0/0xd80 net/socket.c:2566 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2620 __sys_sendmsg net/socket.c:2652 [inline] __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2655 x64_sys_call+0x32fb/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Uninit was created at: slab_post_alloc_hook mm/slub.c:4154 [inline] slab_alloc_node mm/slub.c:4197 [inline] kmem_cache_alloc_node_noprof+0x818/0xf00 mm/slub.c:4249 kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:579 __alloc_skb+0x347/0x7d0 net/core/skbuff.c:670 alloc_skb include/linux/skbuff.h:1336 [inline] vcc_sendmsg+0xb40/0xff0 net/atm/common.c:628 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg+0x330/0x3d0 net/socket.c:727 ____sys_sendmsg+0x7e0/0xd80 net/socket.c:2566 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2620 __sys_sendmsg net/socket.c:2652 [inline] __do_sys_sendmsg net/socket.c:2657 [inline] __se_sys_sendmsg net/socket.c:2655 [inline] __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2655 x64_sys_call+0x32fb/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f CPU: 1 UID: 0 PID: 5798 Comm: syz-executor192 Not tainted 6.16.0-rc1-syzkaller-00010-g2c4a1f3fe03e #0 PREEMPT(undef) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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Meta Information
Published
2025-07-04
Last Modified
2025-12-18
Generated
2026-05-07
AI Q&A
2025-07-04
EPSS Evaluated
2026-05-05
NVD
CVE-2025-38185
Affected Vendors & Products
Showing 15 associated CPEs
Vendor Product Version / Range
linux linux_kernel From 2.6.13 (inc) to 5.4.295 (exc)
linux linux_kernel From 5.5 (inc) to 5.10.239 (exc)
linux linux_kernel From 5.11 (inc) to 5.15.186 (exc)
linux linux_kernel From 5.16 (inc) to 6.1.142 (exc)
linux linux_kernel From 6.2 (inc) to 6.6.95 (exc)
linux linux_kernel From 6.7 (inc) to 6.12.35 (exc)
linux linux_kernel From 6.13 (inc) to 6.15.4 (exc)
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 2.6.12
linux linux_kernel 6.16
linux linux_kernel 6.16
debian debian_linux 11.0
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-401 The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability in the Linux kernel's ATM TCP driver (atmtcp) involves improper handling of socket buffer (skb) lengths in the atmtcp_c_send() function. Specifically, the function accesses skb data assuming it has a valid length after only checking if skb->len is zero, which is insufficient. When skb->len is zero, the skb and associated socket (sk) are leaked because the expected freeing and memory adjustments are not performed. This can lead to memory leaks and potentially unstable kernel behavior. The fix properly frees skb with invalid length to prevent these issues.


How can this vulnerability impact me? :

This vulnerability can cause memory leaks in the Linux kernel when handling ATM TCP socket buffers with invalid lengths. Such leaks may degrade system stability or performance over time and could potentially be exploited to cause denial of service or other unintended behavior in systems using the affected kernel code.


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