On Wed, 05. Aug 14:37, Moritz Barsnick wrote:
On Mon, Jul 20, 2020 at 09:18:55 +0200, Alexander Strasser wrote:
On 2020-07-19 19:47 -0400, Andriy Gelman wrote:
This check seems dead code. Looking at xcb sources, cursor is just an offset in memory from ci so I don't think it can be null here.
But anyway, this part of the patch doesn't really have anything to do with ticket #7312, and should be in a separate patch.
Yes, it's definitely something that was changed in this patch at all. So it's better not to touch it in this patch.
Okay, so I "fixed" dead code. You guys can remove the dead code yourselves then, if you like. ;-)
New patch for the original issue attached, not touching the dead code.
Thanks, Moritz
From e44b7f03354add2272a2739e04aafb38b7ce027f Mon Sep 17 00:00:00 2001 From: Moritz Barsnick <barsnick@gmx.net> Date: Wed, 5 Aug 2020 14:06:53 +0200 Subject: [PATCH] avdevice/xcbgrab: check return values of xcb query functions
Fixes #7312, segmentation fault on close of X11 server
xcb_query_pointer_reply() and xcb_get_geometry_reply() can return NULL if e.g. the X server closes or the connection is lost. This needs to be checked in order to cleanly exit, because the returned pointers are dereferenced later.
Signed-off-by: Moritz Barsnick <barsnick@gmx.net> --- libavdevice/xcbgrab.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/libavdevice/xcbgrab.c b/libavdevice/xcbgrab.c index 6f6b2dbf15..8ef2a30d02 100644 --- a/libavdevice/xcbgrab.c +++ b/libavdevice/xcbgrab.c @@ -425,7 +425,16 @@ static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt) pc = xcb_query_pointer(c->conn, c->screen->root); gc = xcb_get_geometry(c->conn, c->screen->root); p = xcb_query_pointer_reply(c->conn, pc, NULL); + if (!p) { + av_log(s, AV_LOG_ERROR, "Failed to query xcb pointer\n"); + return AVERROR_EXTERNAL; + } geo = xcb_get_geometry_reply(c->conn, gc, NULL); + if (!geo) { + av_log(s, AV_LOG_ERROR, "Failed to get xcb geometry\n"); + free(p); + return AVERROR_EXTERNAL; + } }
if (c->follow_mouse && p->same_screen) -- 2.26.2
lgtm Thanks, -- Andriy