[patch] Fix solib list reading asan error (for PR 8882)

Jan Kratochvil
2014-02-26T22:09:28Z

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Hi,

runtest gdb.base/corefile.exp

==23174== ERROR: AddressSanitizer: heap-use-after-free on address 0x604400008c88 at pc 0x68f0be bp 0x7fffae9d7490 sp 0x7fffae9d7480
READ of size 8 at 0x604400008c88 thread T0
#0 0x68f0bd in svr4_read_so_list (/home/jkratoch/redhat/gdb-clean/gdb/gdb+0x68f0bd)
#1 0x68f64e in svr4_current_sos_direct (/home/jkratoch/redhat/gdb-clean/gdb/gdb+0x68f64e)
#2 0x68f757 in svr4_current_sos (/home/jkratoch/redhat/gdb-clean/gdb/gdb+0x68f757)
#3 0xcebbff in update_solib_list (/home/jkratoch/redhat/gdb-clean/gdb/gdb+0xcebbff)
0x604400008c88 is located 8 bytes inside of 1104-byte region [0x604400008c80,0x6044000090d0)
freed by thread T0 here:
#0 0x7f52677500f9 (/lib64/libasan.so.0+0x160f9)
#1 0xd2c68a in xfree (/home/jkratoch/redhat/gdb-clean/gdb/gdb+0xd2c68a)
#2 0xceb364 in free_so (/home/jkratoch/redhat/gdb-clean/gdb/gdb+0xceb364)
#3 0xca59f8 in do_free_so (/home/jkratoch/redhat/gdb-clean/gdb/gdb+0xca59f8)
#4 0x93432a in do_my_cleanups (/home/jkratoch/redhat/gdb-clean/gdb/gdb+0x93432a)
#5 0x934406 in do_cleanups (/home/jkratoch/redhat/gdb-clean/gdb/gdb+0x934406)
#6 0x68efa9 in svr4_read_so_list (/home/jkratoch/redhat/gdb-clean/gdb/gdb+0x68efa9)

I did not notice it during my review in:
Re: [PATCH v2] Skip vDSO when reading SO list (PR 8882)
https://sourceware.org/ml/gdb-patches/2013-09/msg00888.html

I will check it in.

Jan

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Additional PR 8882 fix.

gdb/
2014-02-26 Jan Kratochvil <jan.kratochvil@redhat.com>

Additional PR 8882 fix.
* solib-svr4.c (svr4_read_so_list): Change first to first_l_name.

diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index e2e173a..6c4dff7 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -1306,7 +1306,7 @@ static int
svr4_read_so_list (CORE_ADDR lm, CORE_ADDR prev_lm,
struct so_list ***link_ptr_ptr, int ignore_first)
{
- struct so_list *first = NULL;
+ CORE_ADDR first_l_name;
CORE_ADDR next_lm;

for (; lm != 0; prev_lm = lm, lm = next_lm)
@@ -1346,7 +1346,7 @@ svr4_read_so_list (CORE_ADDR lm, CORE_ADDR prev_lm,
{
struct svr4_info *info = get_svr4_info ();

- first = new;
+ first_l_name = new->lm_info->l_name;
info->main_lm_addr = new->lm_info->lm_addr;
do_cleanups (old_chain);
continue;
@@ -1361,8 +1361,7 @@ svr4_read_so_list (CORE_ADDR lm, CORE_ADDR prev_lm,
inferior executable, then this is not a normal shared
object, but (most likely) a vDSO. In this case, silently
skip it; otherwise emit a warning. */
- if (first == NULL
- || new->lm_info->l_name != first->lm_info->l_name)
+ if (first_l_name == 0 || new->lm_info->l_name != first_l_name)
warning (_("Can't read pathname for load map: %s."),
safe_strerror (errcode));
do_cleanups (old_chain);