From: Jashank Jeremy <jashank@rulingia.com.au>
To: Po Lu <luangruo@yahoo.com>, Emacs development list <emacs-devel@gnu.org>
Subject: Re: master 242a4b49cb: Minor cleanups to X drag-and-drop code
Date: Sun, 22 May 2022 16:56:15 +1000 [thread overview]
Message-ID: <87v8tyf434.wl-jashank@rulingia.com.au> (raw)
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> diff --git a/src/xterm.c b/src/xterm.c
> index a8745894eb2..a3b7c4ac257 100644
> --- a/src/xterm.c
> +++ b/src/xterm.c
> [...]
> @@ -1977,6 +2012,9 @@ xm_read_drag_receiver_info (struct x_display_info *dpyinfo,
> rec->byteorder = XM_BYTE_ORDER_CUR_FIRST;
> }
>
> + if (data[1] > XM_DRAG_PROTOCOL_VERSION)
> + rc = 0;
> +
> if (tmp_data)
> XFree (tmp_data);
Whilst chasing down the build failure against e465ea816d, I observed
some compiler warnings related to this patch:
.../emacs/src/src/xterm.c:1994:7: warning: variable 'data' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (rc)
^~
.../emacs/src/src/xterm.c:2016:7: note: uninitialized use occurs here
if (data[1] > XM_DRAG_PROTOCOL_VERSION)
^~~~
.../emacs/src/src/xterm.c:1994:3: note: remove the 'if' if its condition is always true
if (rc)
^~~~~~~
.../emacs/src/src/xterm.c:1977:16: note: initialize the variable 'data' to silence this warning
uint8_t *data;
^
= NULL
This looks like a plausible issue --- XGetWindowProperty looks to be
fallible, and in the event it fails we're potentially dereferencing an
uninitialised value. I suspect the check introduced in this commit
should be within the immediately preceding region; however, I do not
know what the implications of such a change would be, and thus won't
concretely suggest one.
~jashank
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next reply other threads:[~2022-05-22 6:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-22 6:56 Jashank Jeremy [this message]
2022-05-22 7:50 ` master 242a4b49cb: Minor cleanups to X drag-and-drop code Po Lu
2022-05-22 7:55 ` Po Lu
-- strict thread matches above, loose matches on Subject: below --
2022-05-20 11:41 Eli Zaretskii
2022-05-20 12:05 ` Po Lu
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