GHSA-6X2C-JC67-WP74
Vulnerability from github – Published: 2025-08-16 12:30 – Updated: 2026-08-10 15:32In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix irq-disabled in local_bh_enable()
The rxrpc_assess_MTU_size() function calls down into the IP layer to find out the MTU size for a route. When accepting an incoming call, this is called from rxrpc_new_incoming_call() which holds interrupts disabled across the code that calls down to it. Unfortunately, the IP layer uses local_bh_enable() which, config dependent, throws a warning if IRQs are enabled:
WARNING: CPU: 1 PID: 5544 at kernel/softirq.c:387 __local_bh_enable_ip+0x43/0xd0 ... RIP: 0010:__local_bh_enable_ip+0x43/0xd0 ... Call Trace: rt_cache_route+0x7e/0xa0 rt_set_nexthop.isra.0+0x3b3/0x3f0 __mkroute_output+0x43a/0x460 ip_route_output_key_hash+0xf7/0x140 ip_route_output_flow+0x1b/0x90 rxrpc_assess_MTU_size.isra.0+0x2a0/0x590 rxrpc_new_incoming_peer+0x46/0x120 rxrpc_alloc_incoming_call+0x1b1/0x400 rxrpc_new_incoming_call+0x1da/0x5e0 rxrpc_input_packet+0x827/0x900 rxrpc_io_thread+0x403/0xb60 kthread+0x2f7/0x310 ret_from_fork+0x2a/0x230 ret_from_fork_asm+0x1a/0x30 ... hardirqs last enabled at (23): _raw_spin_unlock_irq+0x24/0x50 hardirqs last disabled at (24): _raw_read_lock_irq+0x17/0x70 softirqs last enabled at (0): copy_process+0xc61/0x2730 softirqs last disabled at (25): rt_add_uncached_list+0x3c/0x90
Fix this by moving the call to rxrpc_assess_MTU_size() out of rxrpc_init_peer() and further up the stack where it can be done without interrupts disabled.
It shouldn't be a problem for rxrpc_new_incoming_call() to do it after the locks are dropped as pmtud is going to be performed by the I/O thread - and we're in the I/O thread at this point.
{
"affected": [],
"aliases": [
"CVE-2025-38525"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-08-16T12:15:27Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: Fix irq-disabled in local_bh_enable()\n\nThe rxrpc_assess_MTU_size() function calls down into the IP layer to find\nout the MTU size for a route. When accepting an incoming call, this is\ncalled from rxrpc_new_incoming_call() which holds interrupts disabled\nacross the code that calls down to it. Unfortunately, the IP layer uses\nlocal_bh_enable() which, config dependent, throws a warning if IRQs are\nenabled:\n\nWARNING: CPU: 1 PID: 5544 at kernel/softirq.c:387 __local_bh_enable_ip+0x43/0xd0\n...\nRIP: 0010:__local_bh_enable_ip+0x43/0xd0\n...\nCall Trace:\n \u003cTASK\u003e\n rt_cache_route+0x7e/0xa0\n rt_set_nexthop.isra.0+0x3b3/0x3f0\n __mkroute_output+0x43a/0x460\n ip_route_output_key_hash+0xf7/0x140\n ip_route_output_flow+0x1b/0x90\n rxrpc_assess_MTU_size.isra.0+0x2a0/0x590\n rxrpc_new_incoming_peer+0x46/0x120\n rxrpc_alloc_incoming_call+0x1b1/0x400\n rxrpc_new_incoming_call+0x1da/0x5e0\n rxrpc_input_packet+0x827/0x900\n rxrpc_io_thread+0x403/0xb60\n kthread+0x2f7/0x310\n ret_from_fork+0x2a/0x230\n ret_from_fork_asm+0x1a/0x30\n...\nhardirqs last enabled at (23): _raw_spin_unlock_irq+0x24/0x50\nhardirqs last disabled at (24): _raw_read_lock_irq+0x17/0x70\nsoftirqs last enabled at (0): copy_process+0xc61/0x2730\nsoftirqs last disabled at (25): rt_add_uncached_list+0x3c/0x90\n\nFix this by moving the call to rxrpc_assess_MTU_size() out of\nrxrpc_init_peer() and further up the stack where it can be done without\ninterrupts disabled.\n\nIt shouldn\u0027t be a problem for rxrpc_new_incoming_call() to do it after the\nlocks are dropped as pmtud is going to be performed by the I/O thread - and\nwe\u0027re in the I/O thread at this point.",
"id": "GHSA-6x2c-jc67-wp74",
"modified": "2026-08-10T15:32:35Z",
"published": "2025-08-16T12:30:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38525"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2029f21f10dedb88c0f86abffcf8d6c21dcf6040"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8ac0b3baa7d8f732bd9e5cbf1d8b57e4802c6b36"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d94b82d452ca27a200cd67660dc48476386651d8"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e4d2878369d590bf8455e3678a644e503172eafa"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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