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a88c02915d
io_register_iowq_max_workers() walks ctx->tctx_list under ctx->tctx_lock
and dereferences each node's task->io_uring without a NULL check:
list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
tctx = node->task->io_uring;
if (WARN_ON_ONCE(!tctx->io_wq))
continue;
...
}
__io_uring_add_tctx_node() installs the node into ctx->tctx_list (via
io_tctx_install_node(), which does the list_add() under tctx_lock) and
only assigns current->io_uring = tctx afterwards. A task doing its first
io_uring operation on a shared ring therefore has a window in which its
node is already visible on ctx->tctx_list while node->task->io_uring is
still NULL. A concurrent IORING_REGISTER_IOWQ_MAX_WORKERS on the same
ring reads that NULL and dereferences tctx->io_wq:
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
RIP: io_register_iowq_max_workers io_uring/register.c:423
Publish current->io_uring = tctx before installing the node, so any node
visible on ctx->tctx_list always has a valid task->io_uring.
Fixes: 7880174e1e ("io_uring/tctx: clean up __io_uring_add_tctx_node() error handling")
Signed-off-by: Lim HyeonJun <shja0831@gmail.com>
Link: https://patch.msgid.link/20260524110853.115634-1-shja0831@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
418 lines
9.1 KiB
418 lines
9.1 KiB