CVE-2026-31774
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: io_uring/net: fix slab-out-of-bounds read in io_bundle_nbufs() sqe->len is __u32 but gets stored into sr->len which is int. When userspace passes sqe->len values exceeding INT_MAX (e.g. 0xFFFFFFFF), sr->len overflows to a negative value. This negative value propagates through the bundle recv/send path: 1. io_recv(): sel.val = sr->len (ssize_t gets -1) 2. io_recv_buf_select(): arg.max_len = sel->val (size_t gets 0xFFFFFFFFFFFFFFFF) 3. io_ring_buffers_peek(): buf->len is not clamped because max_len is astronomically large 4. iov[].iov_len = 0xFFFFFFFF flows into io_bundle_nbufs() 5. io_bundle_nbufs(): min_t(int, 0xFFFFFFFF, ret) yields -1, causing ret to increase instead of decrease, creating an infinite loop that reads past the allocated iov[] array This results in a slab-out-of-bounds read in io_bundle_nbufs() from the kmalloc-64 slab, as nbufs increments past the allocated iovec entries. BUG: KASAN: slab-out-of-bounds in io_bundle_nbufs+0x128/0x160 Read of size 8 at addr ffff888100ae05c8 by task exp/145 Call Trace: io_bundle_nbufs+0x128/0x160 io_recv_finish+0x117/0xe20 io_recv+0x2db/0x1160 Fix this by rejecting negative sr->len values early in both io_sendmsg_prep() and io_recvmsg_prep(). Since sqe->len is __u32, any value > INT_MAX indicates overflow and is not a valid length.
Severity
HIGH
CVSS score
7.1
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-05-01 15:16:40.720000
Last modified
2026-10-19 20:17:59.037000
View original CVE JSON
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"published": "2026-05-01T15:16:40.720",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/net: fix slab-out-of-bounds read in io_bundle_nbufs()\n\nsqe->len is __u32 but gets stored into sr->len which is int. When\nuserspace passes sqe->len values exceeding INT_MAX (e.g. 0xFFFFFFFF),\nsr->len overflows to a negative value. This negative value propagates\nthrough the bundle recv/send path:\n\n 1. io_recv(): sel.val = sr->len (ssize_t gets -1)\n 2. io_recv_buf_select(): arg.max_len = sel->val (size_t gets\n 0xFFFFFFFFFFFFFFFF)\n 3. io_ring_buffers_peek(): buf->len is not clamped because max_len\n is astronomically large\n 4. iov[].iov_len = 0xFFFFFFFF flows into io_bundle_nbufs()\n 5. io_bundle_nbufs(): min_t(int, 0xFFFFFFFF, ret) yields -1,\n causing ret to increase instead of decrease, creating an\n infinite loop that reads past the allocated iov[] array\n\nThis results in a slab-out-of-bounds read in io_bundle_nbufs() from\nthe kmalloc-64 slab, as nbufs increments past the allocated iovec\nentries.\n\n BUG: KASAN: slab-out-of-bounds in io_bundle_nbufs+0x128/0x160\n Read of size 8 at addr ffff888100ae05c8 by task exp/145\n Call Trace:\n io_bundle_nbufs+0x128/0x160\n io_recv_finish+0x117/0xe20\n io_recv+0x2db/0x1160\n\nFix this by rejecting negative sr->len values early in both\nio_sendmsg_prep() and io_recvmsg_prep(). Since sqe->len is __u32,\nany value > INT_MAX indicates overflow and is not a valid length."
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