From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1944) id 19864384D1AE; Wed, 12 Oct 2022 14:15:45 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 19864384D1AE DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1665584145; bh=SnObwj/JawKB+CF8NSmIQk/RamtZ/n6MZdr5+GCy97o=; h=From:To:Subject:Date:From; b=BEFcRscQs9FUR/TBqByegmH+jYL2lv+U42Aqksxk9X5J2ENhPvWTRxstBS/3o1FkZ FQ30QVXTBM7weaMDQJtiCImJmrmxqKos3GLRhJ7YdF/fzkX98eiTIHJ+4UKxwwaGXR 0XyLY81GJ4TMjHyHtMKA87afzB0aHqDJGlRx8dW0= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Szabolcs Nagy To: glibc-cvs@sourceware.org Subject: [glibc/arm/morello/main] elf: Fix _dl_debug_vdprintf stack buffer underflow X-Act-Checkin: glibc X-Git-Author: Szabolcs Nagy X-Git-Refname: refs/heads/arm/morello/main X-Git-Oldrev: ed157fcccd5dcf2644236084082ebb5159f6cff8 X-Git-Newrev: 059dd1983c8ee1a01c556e3dbe412791f43c2b8a Message-Id: <20221012141545.19864384D1AE@sourceware.org> Date: Wed, 12 Oct 2022 14:15:45 +0000 (GMT) List-Id: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=059dd1983c8ee1a01c556e3dbe412791f43c2b8a commit 059dd1983c8ee1a01c556e3dbe412791f43c2b8a Author: Szabolcs Nagy Date: Tue Oct 11 14:22:35 2022 +0100 elf: Fix _dl_debug_vdprintf stack buffer underflow When printing numbers the alloca buffer size did not consider the optional width parameter for padding. The width is used e.g. by _dl_map_object_from_fd which passes '(int) sizeof (void *) * 2' which can be larger than the buffer size on systems where sizeof (void *) >= 2 * sizeof (unsigned long). But even if large width is not used currently it is better to handle it to avoid surprises. Diff: --- elf/dl-printf.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/elf/dl-printf.c b/elf/dl-printf.c index d3264ba96c..10efa925bd 100644 --- a/elf/dl-printf.c +++ b/elf/dl-printf.c @@ -163,8 +163,11 @@ _dl_debug_vdprintf (int fd, int tag_p, const char *fmt, va_list arg) /* We use alloca() to allocate the buffer with the most pessimistic guess for the size. Using alloca() allows having more than one integer formatting in a call. */ - char *buf = (char *) alloca (1 + 3 * sizeof (unsigned long int)); - char *endp = &buf[1 + 3 * sizeof (unsigned long int)]; + int size = 1 + 3 * sizeof (unsigned long int); + if (width + 1 > size) + size = width + 1; + char *buf = (char *) alloca (size); + char *endp = &buf[size]; char *cp = _itoa (num, endp, *fmt == 'x' ? 16 : 10, 0); /* Pad to the width the user specified. */