From 9039747fb4863c13eaf07f84bb28d50660fb8d85 Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Sat, 10 Jul 2021 09:34:30 +0930 Subject: PR28069, assertion fail in dwarf.c:display_discr_list We shouldn't be asserting on anything to do with leb128 values, or reporting file and line numbers when something unexpected happens. leb128 data is of indeterminate length, perfect for fuzzer mayhem. It would only make sense to assert or report dwarf.c/readelf.c source lines if the code had already sized and sanity checked the leb128 values. After removing the assertions, the testcase then gave: <37> DW_AT_discr_list : 5 byte block: 0 0 0 0 0 (label 0, label 0, label 0, label 0, readelf: Warning: corrupt discr_list - unrecognized discriminant byte 0x5 <3d> DW_AT_encoding : 0 (void) <3e> DW_AT_identifier_case: 0 (case_sensitive) <3f> DW_AT_virtuality : 0 (none) <40> DW_AT_decimal_sign: 5 (trailing separate) So the DW_AT_discr_list was showing more data than just the 5 byte block. That happened due to "end" pointing a long way past the end of block, and uvalue decrementing past zero on one of the leb128 bytes. PR 28069 * dwarf.c (display_discr_list): Remove assertions. Delete "end" parameter, use initial "data" pointer as the end. Formatting. Don't count down bytes as they are read. (read_and_display_attr_value): Adjust display_discr_list call. (read_and_print_leb128): Don't pass __FILE__ and __LINE__ to report_leb_status. * dwarf.h (report_leb_status): Don't report file and line numbers. Delete file and lnum parameters, (READ_ULEB, READ_SLEB): Adjust. --- binutils/ChangeLog | 13 +++++++++++++ binutils/dwarf.c | 24 ++++++++---------------- binutils/dwarf.h | 10 +++++----- 3 files changed, 26 insertions(+), 21 deletions(-) diff --git a/binutils/ChangeLog b/binutils/ChangeLog index be5fd77b838..6f4946b36aa 100644 --- a/binutils/ChangeLog +++ b/binutils/ChangeLog @@ -1,3 +1,16 @@ +2021-07-10 Alan Modra + + PR 28069 + * dwarf.c (display_discr_list): Remove assertions. Delete "end" + parameter, use initial "data" pointer as the end. Formatting. + Don't count down bytes as they are read. + (read_and_display_attr_value): Adjust display_discr_list call. + (read_and_print_leb128): Don't pass __FILE__ and __LINE__ to + report_leb_status. + * dwarf.h (report_leb_status): Don't report file and line + numbers. Delete file and lnum parameters, + (READ_ULEB, READ_SLEB): Adjust. + 2021-07-07 Rainer Orth * configure.ac: Check for strnlen declaration. diff --git a/binutils/dwarf.c b/binutils/dwarf.c index ad1ee97d9bf..fbd5d6aea5a 100644 --- a/binutils/dwarf.c +++ b/binutils/dwarf.c @@ -2280,7 +2280,7 @@ read_and_print_leb128 (unsigned char *data, int status; dwarf_vma val = read_leb128 (data, end, is_signed, bytes_read, &status); if (status != 0) - report_leb_status (status, __FILE__, __LINE__); + report_leb_status (status); else printf ("%s", dwarf_vmatoa (is_signed ? "d" : "u", val)); } @@ -2289,9 +2289,10 @@ static void display_discr_list (unsigned long form, dwarf_vma uvalue, unsigned char * data, - unsigned const char * end, int level) { + unsigned char *end = data; + if (uvalue == 0) { printf ("[default]"); @@ -2320,41 +2321,32 @@ display_discr_list (unsigned long form, return; } - bool is_signed = - (level > 0 && level <= MAX_CU_NESTING) - ? level_type_signed [level - 1] : false; + bool is_signed = (level > 0 && level <= MAX_CU_NESTING + ? level_type_signed [level - 1] : false); printf ("("); - while (uvalue) + while (data < end) { unsigned char discriminant; unsigned int bytes_read; SAFE_BYTE_GET_AND_INC (discriminant, data, 1, end); - -- uvalue; - assert (uvalue > 0); switch (discriminant) { case DW_DSC_label: printf ("label "); read_and_print_leb128 (data, & bytes_read, end, is_signed); - assert (bytes_read <= uvalue && bytes_read > 0); - uvalue -= bytes_read; data += bytes_read; break; case DW_DSC_range: printf ("range "); read_and_print_leb128 (data, & bytes_read, end, is_signed); - assert (bytes_read <= uvalue && bytes_read > 0); - uvalue -= bytes_read; data += bytes_read; printf (".."); read_and_print_leb128 (data, & bytes_read, end, is_signed); - assert (bytes_read <= uvalue && bytes_read > 0); - uvalue -= bytes_read; data += bytes_read; break; @@ -2365,7 +2357,7 @@ display_discr_list (unsigned long form, return; } - if (uvalue) + if (data < end) printf (", "); } @@ -3230,7 +3222,7 @@ read_and_display_attr_value (unsigned long attribute, case DW_AT_discr_list: printf ("\t"); - display_discr_list (form, uvalue, data, end, level); + display_discr_list (form, uvalue, data, level); break; case DW_AT_frame_base: diff --git a/binutils/dwarf.h b/binutils/dwarf.h index 2070c6f3daf..887b720f632 100644 --- a/binutils/dwarf.h +++ b/binutils/dwarf.h @@ -264,12 +264,12 @@ extern unsigned char * get_build_id (void *); #endif static inline void -report_leb_status (int status, const char *file, unsigned long lnum) +report_leb_status (int status) { if ((status & 1) != 0) - error (_("%s:%lu: end of data encountered whilst reading LEB\n"), file, lnum); + error (_("end of data encountered whilst reading LEB\n")); else if ((status & 2) != 0) - error (_("%s:%lu: read LEB value is too large to store in destination variable\n"), file, lnum); + error (_("read LEB value is too large to store in destination variable\n")); } #define SKIP_ULEB(start, end) \ @@ -302,7 +302,7 @@ report_leb_status (int status, const char *file, unsigned long lnum) (var) = _val; \ if ((var) != _val) \ _status |= 2; \ - report_leb_status (_status, __FILE__, __LINE__); \ + report_leb_status (_status); \ } \ while (0) @@ -318,6 +318,6 @@ report_leb_status (int status, const char *file, unsigned long lnum) (var) = _val; \ if ((var) != _val) \ _status |= 2; \ - report_leb_status (_status, __FILE__, __LINE__); \ + report_leb_status (_status); \ } \ while (0) -- cgit v1.2.1