From: "Richard W.M. Jones" Date: Thu, 28 Aug 2014 09:04:21 +0100 Subject: [PATCH] curl: Don't deref NULL pointer in call to aio_poll. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In commit 63f0f45f2e89b60ff8245fec81328ddfde42a303 the following mechanical change was made: if (!state) { - qemu_aio_wait(); + aio_poll(state->s->aio_context, true); } The new code now checks if state is NULL and then dereferences it ('state->s') which is obviously incorrect. This commit replaces state->s->aio_context with bdrv_get_aio_context(bs), fixing this problem. The two other hunks are concerned with getting the BlockDriverState pointer bs to where it is needed. The original bug causes a segfault when using libguestfs to access a VMware vCenter Server and doing any kind of complex read-heavy operations. With this commit the segfault goes away. Signed-off-by: Richard W.M. Jones Reviewed-by: Paolo Bonzini Reviewed-by: Benoît Canet Signed-off-by: Stefan Hajnoczi (cherry picked from commit a2f468e48f8b6559ec9123e94948bc373b788941) --- block/curl.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/block/curl.c b/block/curl.c index 537e257..d28b701 100644 --- a/block/curl.c +++ b/block/curl.c @@ -357,7 +357,7 @@ static void curl_multi_timeout_do(void *arg) #endif } -static CURLState *curl_init_state(BDRVCURLState *s) +static CURLState *curl_init_state(BlockDriverState *bs, BDRVCURLState *s) { CURLState *state = NULL; int i, j; @@ -375,7 +375,7 @@ static CURLState *curl_init_state(BDRVCURLState *s) break; } if (!state) { - aio_poll(state->s->aio_context, true); + aio_poll(bdrv_get_aio_context(bs), true); } } while(!state); @@ -566,7 +566,7 @@ static int curl_open(BlockDriverState *bs, QDict *options, int flags, DPRINTF("CURL: Opening %s\n", file); s->aio_context = bdrv_get_aio_context(bs); s->url = g_strdup(file); - state = curl_init_state(s); + state = curl_init_state(bs, s); if (!state) goto out_noclean; @@ -651,7 +651,7 @@ static void curl_readv_bh_cb(void *p) } // No cache found, so let's start a new request - state = curl_init_state(s); + state = curl_init_state(acb->common.bs, s); if (!state) { acb->common.cb(acb->common.opaque, -EIO); qemu_aio_release(acb);