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author | Mark Rutland <mark.rutland@arm.com> | 2019-05-01 16:59:16 +0100 |
---|---|---|
committer | Jens Axboe <axboe@kernel.dk> | 2019-05-01 10:00:25 -0600 |
commit | d4ef647510b1200fe1c996ff1cbf5ac47eb930cc (patch) | |
tree | a401da70fb7e17552021b6fe1a8f120113996693 /fs/io_uring.c | |
parent | f5eb4d3b92a6a1096ef3480b54782a9409281300 (diff) | |
download | linux-d4ef647510b1200fe1c996ff1cbf5ac47eb930cc.tar.bz2 |
io_uring: avoid page allocation warnings
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
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
-rw-r--r-- | fs/io_uring.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 18cecb6a0151..84efb8956734 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2443,7 +2443,7 @@ 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; } @@ -2535,9 +2535,9 @@ 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) { @@ -2549,7 +2549,7 @@ 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) { @@ -2588,6 +2588,7 @@ 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; } @@ -2610,12 +2611,12 @@ 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; } |