@@ -2364,7 +2364,7 @@ static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx)
if (ctx->account_mem)
io_unaccount_mem(ctx->user, imu->nr_bvecs);
- kfree(imu->bvec);
+ kvfree(imu->bvec);
imu->nr_bvecs = 0;
}
@@ -2456,9 +2456,9 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
if (!pages || nr_pages > got_pages) {
kfree(vmas);
kfree(pages);
- pages = kmalloc_array(nr_pages, sizeof(struct page *),
+ pages = kvmalloc_array(nr_pages, sizeof(struct page *),
GFP_KERNEL);
- vmas = kmalloc_array(nr_pages,
+ vmas = kvmalloc_array(nr_pages,
sizeof(struct vm_area_struct *),
GFP_KERNEL);
if (!pages || !vmas) {
@@ -2470,7 +2470,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
got_pages = nr_pages;
}
- imu->bvec = kmalloc_array(nr_pages, sizeof(struct bio_vec),
+ imu->bvec = kvmalloc_array(nr_pages, sizeof(struct bio_vec),
GFP_KERNEL);
ret = -ENOMEM;
if (!imu->bvec) {
@@ -2509,6 +2509,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
}
if (ctx->account_mem)
io_unaccount_mem(ctx->user, nr_pages);
+ kvfree(imu->bvec);
goto err;
}
@@ -2531,12 +2532,12 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
ctx->nr_user_bufs++;
}
- kfree(pages);
- kfree(vmas);
+ kvfree(pages);
+ kvfree(vmas);
return 0;
err:
- kfree(pages);
- kfree(vmas);
+ kvfree(pages);
+ kvfree(vmas);
io_sqe_buffer_unregister(ctx);
return ret;
}
In io_sqe_buffer_register() we allocate a number of arrays based on the iov_len from the user-provided iov. While we limit iov_len to SZ_1G, we can still attempt to allocate arrays exceeding MAX_ORDER. On a 64-bit system with 4KiB pages, for an iov where iov_base = 0x10 and iov_len = SZ_1G, we'll calculate that nr_pages = 262145. When we try to allocate a corresponding array of (16-byte) bio_vecs, requiring 4194320 bytes, which is greater than 4MiB. This results in SLUB warning that we're trying to allocate greater than MAX_ORDER, and failing the allocation. Avoid this by using kvmalloc() for allocations dependent on the user-provided iov_len. At the same time, fix a leak of imu->bvec when registration fails. Full splat from before this patch: WARNING: CPU: 1 PID: 2314 at mm/page_alloc.c:4595 __alloc_pages_nodemask+0x7ac/0x2938 mm/page_alloc.c:4595 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 2314 Comm: syz-executor326 Not tainted 5.1.0-rc7-dirty #4 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x2f0 include/linux/compiler.h:193 show_stack+0x20/0x30 arch/arm64/kernel/traps.c:158 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x110/0x190 lib/dump_stack.c:113 panic+0x384/0x68c kernel/panic.c:214 __warn+0x2bc/0x2c0 kernel/panic.c:571 report_bug+0x228/0x2d8 lib/bug.c:186 bug_handler+0xa0/0x1a0 arch/arm64/kernel/traps.c:956 call_break_hook arch/arm64/kernel/debug-monitors.c:301 [inline] brk_handler+0x1d4/0x388 arch/arm64/kernel/debug-monitors.c:316 do_debug_exception+0x1a0/0x468 arch/arm64/mm/fault.c:831 el1_dbg+0x18/0x8c __alloc_pages_nodemask+0x7ac/0x2938 mm/page_alloc.c:4595 alloc_pages_current+0x164/0x278 mm/mempolicy.c:2132 alloc_pages include/linux/gfp.h:509 [inline] kmalloc_order+0x20/0x50 mm/slab_common.c:1231 kmalloc_order_trace+0x30/0x2b0 mm/slab_common.c:1243 kmalloc_large include/linux/slab.h:480 [inline] __kmalloc+0x3dc/0x4f0 mm/slub.c:3791 kmalloc_array include/linux/slab.h:670 [inline] io_sqe_buffer_register fs/io_uring.c:2472 [inline] __io_uring_register fs/io_uring.c:2962 [inline] __do_sys_io_uring_register fs/io_uring.c:3008 [inline] __se_sys_io_uring_register fs/io_uring.c:2990 [inline] __arm64_sys_io_uring_register+0x9e0/0x1bc8 fs/io_uring.c:2990 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall arch/arm64/kernel/syscall.c:47 [inline] el0_svc_common.constprop.0+0x148/0x2e0 arch/arm64/kernel/syscall.c:83 el0_svc_handler+0xdc/0x100 arch/arm64/kernel/syscall.c:129 el0_svc+0x8/0xc arch/arm64/kernel/entry.S:948 SMP: stopping secondary CPUs Dumping ftrace buffer: (ftrace buffer empty) Kernel Offset: disabled CPU features: 0x002,23000438 Memory Limit: none Rebooting in 1 seconds.. Fixes: edafccee56ff3167 ("io_uring: add support for pre-mapped user IO buffers") Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-fsdevel@vger.kernel.org Cc: linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- fs/io_uring.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) Since v1: * Use kvmalloc/kvfree * Free imu->bvec in case of error (per Jens)