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h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=G1otjZX0QY+A/Q21txZqVIo8Ep3DaqdFJQeEcUS7su4=; b=yyjEYgG+3/mhxuoAsUQyRjEcRixT3P1wZd869lV7+9xLzZ2hm8WbaT0PTw9hNWd65Su6m8 P2LklQ85/yKpiiH5uPDqSR+oCDMroZn5RN4Df6OzbD7mFURN8WKjRFOS/5qQUQ+2gKwi67 p7BGUMoi8Vwk4aIc8YnY7G/mRAlRqtM= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1695058111; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=G1otjZX0QY+A/Q21txZqVIo8Ep3DaqdFJQeEcUS7su4=; b=mKRMHh4bFDm3qi7i6cBQN00pSRUrCApFqwXaIf1jxbbD5dr+xHfDiDblMvGOziGqDl/79b 1Bzyr1EGv3QnbwAw== From: Fabiano Rosas To: qemu-devel@nongnu.org Cc: Juan Quintela , Peter Xu , Stefan Hajnoczi , Leonardo Bras Subject: [PATCH 3/8] migration: Fix possible races when shutting down the return path Date: Mon, 18 Sep 2023 14:28:17 -0300 Message-Id: <20230918172822.19052-4-farosas@suse.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230918172822.19052-1-farosas@suse.de> References: <20230918172822.19052-1-farosas@suse.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2001:67c:2178:6::1c; envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @suse.de) X-ZM-MESSAGEID: 1695058160177100001 Content-Type: text/plain; charset="utf-8" We cannot call qemu_file_shutdown() on the return path file without taking the file lock. The return path thread could be running it's cleanup code and have just cleared the from_dst_file pointer. Checking ms->to_dst_file for errors could also race with migrate_fd_cleanup() which clears the to_dst_file pointer. Protect both accesses by taking the file lock. This was caught by inspection, it should be rare, but the next patches will start calling this code from other places, so let's do the correct thing. Reviewed-by: Peter Xu Signed-off-by: Fabiano Rosas --- migration/migration.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index d426b69ada..15b7258bb2 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -2064,17 +2064,18 @@ static int open_return_path_on_source(MigrationStat= e *ms, static int await_return_path_close_on_source(MigrationState *ms) { /* - * If this is a normal exit then the destination will send a SHUT and = the - * rp_thread will exit, however if there's an error we need to cause - * it to exit. + * If this is a normal exit then the destination will send a SHUT + * and the rp_thread will exit, however if there's an error we + * need to cause it to exit. shutdown(2), if we have it, will + * cause it to unblock if it's stuck waiting for the destination. */ - if (qemu_file_get_error(ms->to_dst_file) && ms->rp_state.from_dst_file= ) { - /* - * shutdown(2), if we have it, will cause it to unblock if it's st= uck - * waiting for the destination. - */ - qemu_file_shutdown(ms->rp_state.from_dst_file); + WITH_QEMU_LOCK_GUARD(&ms->qemu_file_lock) { + if (ms->to_dst_file && ms->rp_state.from_dst_file && + qemu_file_get_error(ms->to_dst_file)) { + qemu_file_shutdown(ms->rp_state.from_dst_file); + } } + trace_await_return_path_close_on_source_joining(); qemu_thread_join(&ms->rp_state.rp_thread); ms->rp_state.rp_thread_created =3D false; --=20 2.35.3