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[PATCH] readelf: Make sure print_form_data always consumes DW_FORM_strx[1234] data.
- From: Mark Wielaard <mark at klomp dot org>
- To: elfutils-devel at sourceware dot org
- Cc: Mark Wielaard <mark at klomp dot org>
- Date: Thu, 14 Jun 2018 01:10:12 +0200
- Subject: [PATCH] readelf: Make sure print_form_data always consumes DW_FORM_strx[1234] data.
Found by afl-fuzz. When printing DW_FORM_strx[1234] data eu-readelf didn't
increase readp which meant eu-readelf would keep printing the same line
dirs or files encoded with strx[1234] names. This meant that for insane
large dir or file counts eu-readelf would just keep printing endlessly
because we never reached and of the .debug_line buffer.
Signed-off-by: Mark Wielaard <mark@klomp.org>
---
libdw/ChangeLog | 4 ++++
libdw/memory-access.h | 5 +++++
src/ChangeLog | 5 +++++
src/readelf.c | 12 ++++++------
4 files changed, 20 insertions(+), 6 deletions(-)
diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index 78321654..6492c976 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,7 @@
+2018-06-12 Mark Wielaard <mark@klomp.org>
+
+ * memory-access.h (read_3ubyte_unaligned_inc): New define.
+
2018-06-12 Mark Wielaard <mark@klomp.org>
* libdw.h (__libdw_dieabbrev): Set die->abbrev to DWARF_END_ABBREV
diff --git a/libdw/memory-access.h b/libdw/memory-access.h
index 22918cb9..a39ad6d2 100644
--- a/libdw/memory-access.h
+++ b/libdw/memory-access.h
@@ -362,6 +362,11 @@ read_3ubyte_unaligned (Dwarf *dbg, const unsigned char *p)
}
+#define read_3ubyte_unaligned_inc(Dbg, Addr) \
+ ({ uint32_t t_ = read_2ubyte_unaligned (Dbg, Addr); \
+ Addr = (__typeof (Addr)) (((uintptr_t) (Addr)) + 3); \
+ t_; })
+
#define read_addr_unaligned_inc(Nbytes, Dbg, Addr) \
(assert ((Nbytes) == 4 || (Nbytes) == 8), \
((Nbytes) == 4 ? read_4ubyte_unaligned_inc (Dbg, Addr) \
diff --git a/src/ChangeLog b/src/ChangeLog
index fd45405f..fbbb9acb 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,8 @@
+2018-06-12 Mark Wielaard <mark@klomp.org>
+
+ * print_form_data): Don't increase strreadp after use. Do
+ increase readp for DW_FORM_strx[1234].
+
2018-06-11 Mark Wielaard <mark@klomp.org>
* readelf.c (print_form_data): Don't reuse readp and readendp when
diff --git a/src/readelf.c b/src/readelf.c
index f1858971..17d91735 100644
--- a/src/readelf.c
+++ b/src/readelf.c
@@ -7994,9 +7994,9 @@ print_form_data (Dwarf *dbg, int form, const unsigned char *readp,
{
Dwarf_Off idx;
if (offset_len == 8)
- idx = read_8ubyte_unaligned_inc (dbg, strreadp);
+ idx = read_8ubyte_unaligned (dbg, strreadp);
else
- idx = read_4ubyte_unaligned_inc (dbg, strreadp);
+ idx = read_4ubyte_unaligned (dbg, strreadp);
data = dbg->sectiondata[IDX_debug_str];
if (data == NULL || idx >= data->d_size
@@ -8013,25 +8013,25 @@ print_form_data (Dwarf *dbg, int form, const unsigned char *readp,
case DW_FORM_strx1:
if (readendp - readp < 1)
goto invalid_data;
- val = *readp;
+ val = *readp++;
goto strx_val;
case DW_FORM_strx2:
if (readendp - readp < 2)
goto invalid_data;
- val = read_2ubyte_unaligned (dbg, readp);
+ val = read_2ubyte_unaligned_inc (dbg, readp);
goto strx_val;
case DW_FORM_strx3:
if (readendp - readp < 3)
goto invalid_data;
- val = read_3ubyte_unaligned (dbg, readp);
+ val = read_3ubyte_unaligned_inc (dbg, readp);
goto strx_val;
case DW_FORM_strx4:
if (readendp - readp < 4)
goto invalid_data;
- val = read_4ubyte_unaligned (dbg, readp);
+ val = read_4ubyte_unaligned_inc (dbg, readp);
goto strx_val;
default:
--
2.17.0