From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57723) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bHoYV-0002LK-1S for qemu-devel@nongnu.org; Tue, 28 Jun 2016 04:39:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bHoYR-0006oT-Lq for qemu-devel@nongnu.org; Tue, 28 Jun 2016 04:39:37 -0400 Received: from mail-wm0-x242.google.com ([2a00:1450:400c:c09::242]:33256) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bHoYR-0006oM-F1 for qemu-devel@nongnu.org; Tue, 28 Jun 2016 04:39:35 -0400 Received: by mail-wm0-x242.google.com with SMTP id r201so3847997wme.0 for ; Tue, 28 Jun 2016 01:39:35 -0700 (PDT) Sender: Paolo Bonzini From: Paolo Bonzini Date: Tue, 28 Jun 2016 10:39:28 +0200 Message-Id: <1467103170-5784-2-git-send-email-pbonzini@redhat.com> In-Reply-To: <1467103170-5784-1-git-send-email-pbonzini@redhat.com> References: <1467103170-5784-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 1/3] m25p80: do not put iovec on the stack List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: clg@kaod.org When doing a read-modify-write cycle, QEMU uses the iovec after returning from blk_aio_pwritev. m25p80 puts the iovec on the stack of blk_aio_pwritev's caller, which causes trouble in this case. This has been a problem since commit 243e6f6 ("m25p80: Switch to byte-based block access", 2016-05-12) started doing writes at a smaller granularity than 512 bytes. In principle however it could have broken before when using -drive if=mtd,cache=none on a disk with 4K native sectors. Signed-off-by: Paolo Bonzini --- hw/block/m25p80.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c index 09b4767..dd6714d 100644 --- a/hw/block/m25p80.c +++ b/hw/block/m25p80.c @@ -446,6 +446,11 @@ static inline Manufacturer get_man(Flash *s) static void blk_sync_complete(void *opaque, int ret) { + QEMUIOVector *iov = opaque; + + qemu_iovec_destroy(iov); + g_free(iov); + /* do nothing. Masters do not directly interact with the backing store, * only the working copy so no mutexing required. */ @@ -453,31 +458,31 @@ static void blk_sync_complete(void *opaque, int ret) static void flash_sync_page(Flash *s, int page) { - QEMUIOVector iov; + QEMUIOVector *iov = g_new(QEMUIOVector, 1); if (!s->blk || blk_is_read_only(s->blk)) { return; } - qemu_iovec_init(&iov, 1); - qemu_iovec_add(&iov, s->storage + page * s->pi->page_size, + qemu_iovec_init(iov, 1); + qemu_iovec_add(iov, s->storage + page * s->pi->page_size, s->pi->page_size); - blk_aio_pwritev(s->blk, page * s->pi->page_size, &iov, 0, - blk_sync_complete, NULL); + blk_aio_pwritev(s->blk, page * s->pi->page_size, iov, 0, + blk_sync_complete, iov); } static inline void flash_sync_area(Flash *s, int64_t off, int64_t len) { - QEMUIOVector iov; + QEMUIOVector *iov = g_new(QEMUIOVector, 1); if (!s->blk || blk_is_read_only(s->blk)) { return; } assert(!(len % BDRV_SECTOR_SIZE)); - qemu_iovec_init(&iov, 1); - qemu_iovec_add(&iov, s->storage + off, len); - blk_aio_pwritev(s->blk, off, &iov, 0, blk_sync_complete, NULL); + qemu_iovec_init(iov, 1); + qemu_iovec_add(iov, s->storage + off, len); + blk_aio_pwritev(s->blk, off, iov, 0, blk_sync_complete, iov); } static void flash_erase(Flash *s, int offset, FlashCMD cmd) -- 2.7.4