From 6694c4110a37bc951d01132d6e56445d57350627 Mon Sep 17 00:00:00 2001 From: Jan Kratochvil Date: Tue, 19 Aug 2014 22:55:10 +0200 Subject: [PATCH] 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 Fix -fsanitize=address on unreadable inferior strings. * valprint.c (val_print_string): Fix access before BUFFER. --- gdb/ChangeLog | 5 +++++ gdb/valprint.c | 6 ++++-- 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 + + Fix -fsanitize=address on unreadable inferior strings. + * valprint.c (val_print_string): Fix access before BUFFER. + 2014-08-19 Simon Marchi * 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; -- 2.7.4