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From f2e33c3268db9adf8e57e991676ed0d5ac74e8a8 Mon Sep 17 00:00:00 2001
From: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date: Mon, 23 Aug 2021 08:11:54 +0530
Subject: [PATCH] mtrace: Fix output with PIE and ASLR [BZ #22716]
Record only the relative address of the caller in mtrace file. Use
LD_TRACE_PRELINKING to get the executable as well as binary vs
executable load offsets so that we may compute a base to add to the
relative address in the mtrace file. This allows us to get a valid
address to pass to addr2line in all cases.
Fixes BZ #22716.
Co-authored-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Andreas Schwab <schwab@linux-m68k.org>
Reviewed-by: DJ Delorie <dj@redhat.com>
---
malloc/mtrace-impl.c | 6 +++---
malloc/mtrace.pl | 15 +++++++--------
2 files changed, 10 insertions(+), 11 deletions(-)
diff --git a/malloc/mtrace-impl.c b/malloc/mtrace-impl.c
index 83008ca..f5f19c2 100644
--- a/malloc/mtrace-impl.c
+++ b/malloc/mtrace-impl.c
@@ -65,9 +65,9 @@ tr_where (const void *caller, Dl_info *info)
offset);
}
- fprintf (mallstream, "@ %s%s%s[%p] ", info->dli_fname ? : "",
- info->dli_fname ? ":" : "",
- buf, caller);
+ fprintf (mallstream, "@ %s%s%s[0x%" PRIxPTR "] ",
+ info->dli_fname ? : "", info->dli_fname ? ":" : "", buf,
+ caller - info->dli_fbase);
}
else
fprintf (mallstream, "@ [%p] ", caller);
diff --git a/malloc/mtrace.pl b/malloc/mtrace.pl
index 6f49c83..b1073a1 100644
--- a/malloc/mtrace.pl
+++ b/malloc/mtrace.pl
@@ -75,11 +75,15 @@ if ($#ARGV == 0) {
} else {
$prog = "./$binary";
}
- if (open (LOCS, "env LD_TRACE_LOADED_OBJECTS=1 $prog |")) {
+ # Set the environment variable LD_TRACE_PRELINKING to an empty string so
+ # that we trigger tracing but do not match with the executable or any of
+ # its dependencies.
+ if (open (LOCS, "env LD_TRACE_PRELINKING= $prog |")) {
while (<LOCS>) {
chop;
- if (/^.*=> (.*) .(0x[0123456789abcdef]*).$/) {
+ if (/^.*=> (.*) \((0x[0123456789abcdef]*), (0x[0123456789abcdef]*).*/) {
$locs{$1} = $2;
+ $rel{$1} = hex($2) - hex($3);
}
}
close (LOCS);
@@ -110,12 +114,7 @@ sub location {
my $addr = $2;
my $searchaddr;
return $cache{$addr} if (exists $cache{$addr});
- if ($locs{$prog} ne "") {
- $searchaddr = sprintf "%#x", $addr - $locs{$prog};
- } else {
- $searchaddr = $addr;
- $prog = $binary;
- }
+ $searchaddr = sprintf "%#x", hex($addr) + $rel{$prog};
if ($binary ne "" && open (ADDR, "addr2line -e $prog $searchaddr|")) {
my $line = <ADDR>;
chomp $line;
--
1.8.3.1
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