* [Qemu-devel] [PATCH] util/async: avoid NULL pointer dereference
@ 2018-06-11 7:04 Jie Wang
2018-06-11 9:29 ` Fam Zheng
0 siblings, 1 reply; 2+ messages in thread
From: Jie Wang @ 2018-06-11 7:04 UTC (permalink / raw)
To: qemu-devel, qemu-block
Cc: famz, stefanha, eblake, eric.fangyi, wu.wubin, wangjie88
if laio_init create linux_aio failed and return NULL, NULL pointer
dereference will occur when laio_attach_aio_context dereference
linux_aio in aio_get_linux_aio, so add assert to avoid it.
Signed-off-by: Jie Wang <wangjie88@huawei.com>
---
util/async.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/util/async.c b/util/async.c
index 03f62787f2..7766bcd8bc 100644
--- a/util/async.c
+++ b/util/async.c
@@ -327,6 +327,7 @@ LinuxAioState *aio_get_linux_aio(AioContext *ctx)
{
if (!ctx->linux_aio) {
ctx->linux_aio = laio_init();
+ assert(ctx->linux_aio);
laio_attach_aio_context(ctx->linux_aio, ctx);
}
return ctx->linux_aio;
--
2.15.0.windows.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [Qemu-devel] [PATCH] util/async: avoid NULL pointer dereference
2018-06-11 7:04 [Qemu-devel] [PATCH] util/async: avoid NULL pointer dereference Jie Wang
@ 2018-06-11 9:29 ` Fam Zheng
0 siblings, 0 replies; 2+ messages in thread
From: Fam Zheng @ 2018-06-11 9:29 UTC (permalink / raw)
To: Jie Wang; +Cc: qemu-devel, qemu-block, stefanha, eblake, eric.fangyi, wu.wubin
On Mon, 06/11 15:04, Jie Wang wrote:
> if laio_init create linux_aio failed and return NULL, NULL pointer
> dereference will occur when laio_attach_aio_context dereference
> linux_aio in aio_get_linux_aio, so add assert to avoid it.
>
> Signed-off-by: Jie Wang <wangjie88@huawei.com>
> ---
> util/async.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/util/async.c b/util/async.c
> index 03f62787f2..7766bcd8bc 100644
> --- a/util/async.c
> +++ b/util/async.c
> @@ -327,6 +327,7 @@ LinuxAioState *aio_get_linux_aio(AioContext *ctx)
> {
> if (!ctx->linux_aio) {
> ctx->linux_aio = laio_init();
> + assert(ctx->linux_aio);
> laio_attach_aio_context(ctx->linux_aio, ctx);
> }
> return ctx->linux_aio;
> --
I'm afraid this is not the correct fix. If laio_init() can fail, this function
should skip laio_attach_aio_context() and return NULL, then callers should check
the return value and handle the error. E.g. Set s->use_linux_aio to false and
fall back to posix I/O, and perhaps report the error with error_report. Or even
better, call laio_init during raw_open and use error_setg(errp, ...).
assert() will simply crash the program, it is not the right way to catch errors.
Fam
^ permalink raw reply [flat|nested] 2+ messages in thread
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