From 362a9e65289284f36403058eea2462d0330c1f24 Mon Sep 17 00:00:00 2001 From: Yang Yingliang Date: Tue, 20 Jul 2021 16:38:05 +0800 Subject: [PATCH] io_uring: fix memleak in io_init_wq_offload() I got memory leak report when doing fuzz test: BUG: memory leak unreferenced object 0xffff888107310a80 (size 96): comm "syz-executor.6", pid 4610, jiffies 4295140240 (age 20.135s) hex dump (first 32 bytes): 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... backtrace: [<000000001974933b>] kmalloc include/linux/slab.h:591 [inline] [<000000001974933b>] kzalloc include/linux/slab.h:721 [inline] [<000000001974933b>] io_init_wq_offload fs/io_uring.c:7920 [inline] [<000000001974933b>] io_uring_alloc_task_context+0x466/0x640 fs/io_uring.c:7955 [<0000000039d0800d>] __io_uring_add_tctx_node+0x256/0x360 fs/io_uring.c:9016 [<000000008482e78c>] io_uring_add_tctx_node fs/io_uring.c:9052 [inline] [<000000008482e78c>] __do_sys_io_uring_enter fs/io_uring.c:9354 [inline] [<000000008482e78c>] __se_sys_io_uring_enter fs/io_uring.c:9301 [inline] [<000000008482e78c>] __x64_sys_io_uring_enter+0xabc/0xc20 fs/io_uring.c:9301 [<00000000b875f18f>] do_syscall_x64 arch/x86/entry/common.c:50 [inline] [<00000000b875f18f>] do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80 [<000000006b0a8484>] entry_SYSCALL_64_after_hwframe+0x44/0xae CPU0 CPU1 io_uring_enter io_uring_enter io_uring_add_tctx_node io_uring_add_tctx_node __io_uring_add_tctx_node __io_uring_add_tctx_node io_uring_alloc_task_context io_uring_alloc_task_context io_init_wq_offload io_init_wq_offload hash = kzalloc hash = kzalloc ctx->hash_map = hash ctx->hash_map = hash <- one of the hash is leaked When calling io_uring_enter() in parallel, the 'hash_map' will be leaked, add uring_lock to protect 'hash_map'. Fixes: e941894eae31 ("io-wq: make buffered file write hashed work map per-ctx") Reported-by: Hulk Robot Signed-off-by: Yang Yingliang Reviewed-by: Pavel Begunkov Link: https://lore.kernel.org/r/20210720083805.3030730-1-yangyingliang@huawei.com Signed-off-by: Jens Axboe --- fs/io_uring.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 6486b54..fe3d948 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7905,15 +7905,19 @@ static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx, struct io_wq_data data; unsigned int concurrency; + mutex_lock(&ctx->uring_lock); hash = ctx->hash_map; if (!hash) { hash = kzalloc(sizeof(*hash), GFP_KERNEL); - if (!hash) + if (!hash) { + mutex_unlock(&ctx->uring_lock); return ERR_PTR(-ENOMEM); + } refcount_set(&hash->refs, 1); init_waitqueue_head(&hash->wait); ctx->hash_map = hash; } + mutex_unlock(&ctx->uring_lock); data.hash = hash; data.task = task; -- 2.7.4