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authorJan Kratochvil <jan.kratochvil@redhat.com>2014-08-19 22:55:10 +0200
committerJan Kratochvil <jan.kratochvil@redhat.com>2014-08-19 22:55:10 +0200
commit6694c4110a37bc951d01132d6e56445d57350627 (patch)
tree817a90a208ffc14ea5b6893334e6b12ffa658600
parent0718a8da7b359f184e1b3a866645cc2f9611771b (diff)
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Fix -fsanitize=address on unreadable inferior strings
echo 'void f(char *s){}main(){f((char *)1);}'|gcc -g -x c -;../gdb ./a.out -ex 'b f' -ex r ====ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000aaccf at pc 0x96eea7 bp 0x7fff75bdbc90 sp 0x7fff75bdbc80 READ of size 1 at 0x6020000aaccf thread T0 #0 0x96eea6 in extract_unsigned_integer .../gdb/findvar.c:108 #1 0x9df02b in val_print_string .../gdb/valprint.c:2513 [...] 0x6020000aaccf is located 1 bytes to the left of 8-byte region [0x6020000aacd0,0x6020000aacd8) allocated by thread T0 here: #0 0x7f45fad26b97 in malloc (/lib64/libasan.so.1+0x57b97) #1 0xdb3409 in xmalloc common/common-utils.c:45 #2 0x9d8cf9 in read_string .../gdb/valprint.c:1845 #3 0x9defca in val_print_string .../gdb/valprint.c:2502 [..] ====ABORTING gdb/ 2014-08-18 Jan Kratochvil <jan.kratochvil@redhat.com> Fix -fsanitize=address on unreadable inferior strings. * valprint.c (val_print_string): Fix access before BUFFER.
-rw-r--r--gdb/ChangeLog5
-rw-r--r--gdb/valprint.c6
2 files changed, 9 insertions, 2 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index f35ba1b..6704916 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2014-08-19 Jan Kratochvil <jan.kratochvil@redhat.com>
+
+ Fix -fsanitize=address on unreadable inferior strings.
+ * valprint.c (val_print_string): Fix access before BUFFER.
+
2014-08-19 Simon Marchi <simon.marchi@ericsson.com>
* target.c (target_struct_size): Remove.
diff --git a/gdb/valprint.c b/gdb/valprint.c
index d3ab267..a87d67c 100644
--- a/gdb/valprint.c
+++ b/gdb/valprint.c
@@ -2510,8 +2510,10 @@ val_print_string (struct type *elttype, const char *encoding,
LEN is -1. */
/* Determine found_nul by looking at the last character read. */
- found_nul = extract_unsigned_integer (buffer + bytes_read - width, width,
- byte_order) == 0;
+ found_nul = 0;
+ if (bytes_read >= width)
+ found_nul = extract_unsigned_integer (buffer + bytes_read - width, width,
+ byte_order) == 0;
if (len == -1 && !found_nul)
{
gdb_byte *peekbuf;