From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1791) id 6144A3858004; Mon, 5 Feb 2024 18:40:00 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6144A3858004 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1707158400; bh=hthBqNUQR9ZP8zO87003wtc82d/lGOcWVKbl0ds/RVc=; h=From:To:Subject:Date:From; b=uqh6KMuB0wzogeaKe8aM1F5IxFiUIXE5RYyK00UKSpXLOcm4BOAJEOly4Zgwwc1ws P/oS3qOlHk47uHWbdILp+vkAJPhthuMAKflDo4Sr4xQtA5js3wNnz2gkFnUHQwYhid BukilrynnoYADgi6qMI1HH68xJHBXXTJY7orKkNE= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Adhemerval Zanella To: glibc-cvs@sourceware.org Subject: [glibc] arm: Remove wrong ldr from _dl_start_user (BZ 31339) X-Act-Checkin: glibc X-Git-Author: Adhemerval Zanella X-Git-Refname: refs/heads/master X-Git-Oldrev: 2e80f139376450acdb7d879d799439578a41810e X-Git-Newrev: 1e25112dc0cb2515d27d8d178b1ecce778a9d37a Message-Id: <20240205184000.6144A3858004@sourceware.org> Date: Mon, 5 Feb 2024 18:40:00 +0000 (GMT) List-Id: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=1e25112dc0cb2515d27d8d178b1ecce778a9d37a commit 1e25112dc0cb2515d27d8d178b1ecce778a9d37a Author: Adhemerval Zanella Date: Mon Feb 5 16:10:24 2024 +0000 arm: Remove wrong ldr from _dl_start_user (BZ 31339) The commit 49d877a80b29d3002887b084eec6676d9f5fec18 (arm: Remove _dl_skip_args usage) removed the _SKIP_ARGS literal, which was previously loader to r4 on loader _start. However, the cleanup did not remove the following 'ldr r4, [sl, r4]' on _dl_start_user, used to check to skip the arguments after ld self-relocations. In my testing, the kernel initially set r4 to 0, which makes the ldr instruction just read the _GLOBAL_OFFSET_TABLE_. However, since r4 is a callee-saved register; a different runtime might not zero initialize it and thus trigger an invalid memory access. Checked on arm-linux-gnu. Reported-by: Adrian Ratiu Reviewed-by: Szabolcs Nagy Diff: --- sysdeps/arm/dl-machine.h | 1 - 1 file changed, 1 deletion(-) diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h index b857bbc868..dd1a0f6b6e 100644 --- a/sysdeps/arm/dl-machine.h +++ b/sysdeps/arm/dl-machine.h @@ -139,7 +139,6 @@ _start:\n\ _dl_start_user:\n\ adr r6, .L_GET_GOT\n\ add sl, sl, r6\n\ - ldr r4, [sl, r4]\n\ @ save the entry point in another register\n\ mov r6, r0\n\ @ get the original arg count\n\