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mtrace: Fix output with PIE and ASLR [BZ #22716]

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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>
This commit is contained in:
Siddhesh Poyarekar
2021-08-23 08:11:54 +05:30
parent 78c9ec9000
commit f2e33c3268
2 changed files with 10 additions and 11 deletions
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6
malloc/mtrace-impl.c
View File

@@ -65,9 +65,9 @@ tr_where (const void *caller, Dl_info *info)
offset); offset);
} }
fprintf (mallstream, "@ %s%s%s[%p] ", info->dli_fname ? : "", fprintf (mallstream, "@ %s%s%s[0x%" PRIxPTR "] ",
info->dli_fname ? ":" : "", info->dli_fname ? : "", info->dli_fname ? ":" : "", buf,
buf, caller); caller - info->dli_fbase);
} }
else else
fprintf (mallstream, "@ [%p] ", caller); fprintf (mallstream, "@ [%p] ", caller);

15
malloc/mtrace.pl
View File

@@ -75,11 +75,15 @@ if ($#ARGV == 0) {
} else { } else {
$prog = "./$binary"; $prog = "./$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= $prog |")) {
while (<LOCS>) { while (<LOCS>) {
chop; chop;
if (/^.*=> (.*) .(0x[0123456789abcdef]*).$/) { if (/^.*=> (.*) \((0x[0123456789abcdef]*), (0x[0123456789abcdef]*).*/) {
$locs{$1} = $2; $locs{$1} = $2;
$rel{$1} = hex($2) - hex($3);
} }
} }
close (LOCS); close (LOCS);
@@ -110,12 +114,7 @@ sub location {
my $addr = $2; my $addr = $2;
my $searchaddr; my $searchaddr;
return $cache{$addr} if (exists $cache{$addr}); return $cache{$addr} if (exists $cache{$addr});
if ($locs{$prog} ne "") { $searchaddr = sprintf "%#x", hex($addr) + $rel{$prog};
$searchaddr = sprintf "%#x", $addr - $locs{$prog};
} else {
$searchaddr = $addr;
$prog = $binary;
}
if ($binary ne "" && open (ADDR, "addr2line -e $prog $searchaddr|")) { if ($binary ne "" && open (ADDR, "addr2line -e $prog $searchaddr|")) {
my $line = <ADDR>; my $line = <ADDR>;
chomp $line; chomp $line;