#include "gdb_assert.h"
#include "gdb_string.h"
+#include "complaints.h"
#include "dwarf2-frame.h"
/* Call Frame Information (CFI). */
#define DW64_CIE_ID ~0
#endif
-/* Read a CIE or FDE in BUF and decode it. */
+static char *decode_frame_entry (struct comp_unit *unit, char *start,
+ int eh_frame_p);
+/* Decode the next CIE or FDE. Return NULL if invalid input, otherwise
+ the next byte to be processed. */
static char *
-decode_frame_entry (struct comp_unit *unit, char *buf, int eh_frame_p)
+decode_frame_entry_1 (struct comp_unit *unit, char *start, int eh_frame_p)
{
+ char *buf;
LONGEST length;
unsigned int bytes_read;
- int dwarf64_p = 0;
- ULONGEST cie_id = DW_CIE_ID;
+ int dwarf64_p;
+ ULONGEST cie_id;
ULONGEST cie_pointer;
- char *start = buf;
char *end;
+ buf = start;
length = read_initial_length (unit->abfd, buf, &bytes_read);
buf += bytes_read;
end = buf + length;
+ /* Are we still within the section? */
+ if (end > unit->dwarf_frame_buffer + unit->dwarf_frame_size)
+ return NULL;
+
if (length == 0)
return end;
- if (bytes_read == 12)
- dwarf64_p = 1;
+ /* Distinguish between 32 and 64-bit encoded frame info. */
+ dwarf64_p = (bytes_read == 12);
- /* In a .eh_frame section, zero is used to distinguish CIEs from
- FDEs. */
+ /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs. */
if (eh_frame_p)
cie_id = 0;
else if (dwarf64_p)
cie_id = DW64_CIE_ID;
+ else
+ cie_id = DW_CIE_ID;
if (dwarf64_p)
{
cie->encoding = encoding_for_size (unit->addr_size);
/* Check version number. */
- gdb_assert (read_1_byte (unit->abfd, buf) == DW_CIE_VERSION);
+ if (read_1_byte (unit->abfd, buf) != DW_CIE_VERSION)
+ return NULL;
buf += 1;
/* Interpret the interesting bits of the augmentation. */
length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
buf += bytes_read;
+ if (buf > end)
+ return NULL;
cie->initial_instructions = buf + length;
augmentation++;
}
/* This is a FDE. */
struct dwarf2_fde *fde;
+ /* In an .eh_frame section, the CIE pointer is the delta between the
+ address within the FDE where the CIE pointer is stored and the
+ address of the CIE. Convert it to an offset into the .eh_frame
+ section. */
if (eh_frame_p)
{
- /* In an .eh_frame section, the CIE pointer is the delta
- between the address within the FDE where the CIE pointer
- is stored and the address of the CIE. Convert it to an
- offset into the .eh_frame section. */
cie_pointer = buf - unit->dwarf_frame_buffer - cie_pointer;
cie_pointer -= (dwarf64_p ? 8 : 4);
}
+ /* In either case, validate the result is still within the section. */
+ if (cie_pointer >= unit->dwarf_frame_size)
+ return NULL;
+
fde = (struct dwarf2_fde *)
obstack_alloc (&unit->objfile->psymbol_obstack,
sizeof (struct dwarf2_fde));
length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
buf += bytes_read + length;
+ if (buf > end)
+ return NULL;
}
fde->instructions = buf;
return end;
}
+
+/* Read a CIE or FDE in BUF and decode it. */
+static char *
+decode_frame_entry (struct comp_unit *unit, char *start, int eh_frame_p)
+{
+ enum { NONE, ALIGN4, ALIGN8, FAIL } workaround = NONE;
+ char *ret;
+ const char *msg;
+ ptrdiff_t start_offset;
+
+ while (1)
+ {
+ ret = decode_frame_entry_1 (unit, start, eh_frame_p);
+ if (ret != NULL)
+ break;
+
+ /* We have corrupt input data of some form. */
+
+ /* ??? Try, weakly, to work around compiler/assembler/linker bugs
+ and mismatches wrt padding and alignment of debug sections. */
+ /* Note that there is no requirement in the standard for any
+ alignment at all in the frame unwind sections. Testing for
+ alignment before trying to interpret data would be incorrect.
+
+ However, GCC traditionally arranged for frame sections to be
+ sized such that the FDE length and CIE fields happen to be
+ aligned (in theory, for performance). This, unfortunately,
+ was done with .align directives, which had the side effect of
+ forcing the section to be aligned by the linker.
+
+ This becomes a problem when you have some other producer that
+ creates frame sections that are not as strictly aligned. That
+ produces a hole in the frame info that gets filled by the
+ linker with zeros.
+
+ The GCC behaviour is arguably a bug, but it's effectively now
+ part of the ABI, so we're now stuck with it, at least at the
+ object file level. A smart linker may decide, in the process
+ of compressing duplicate CIE information, that it can rewrite
+ the entire output section without this extra padding. */
+
+ start_offset = start - unit->dwarf_frame_buffer;
+ if (workaround < ALIGN4 && (start_offset & 3) != 0)
+ {
+ start += 4 - (start_offset & 3);
+ workaround = ALIGN4;
+ continue;
+ }
+ if (workaround < ALIGN8 && (start_offset & 7) != 0)
+ {
+ start += 8 - (start_offset & 7);
+ workaround = ALIGN8;
+ continue;
+ }
+
+ /* Nothing left to try. Arrange to return as if we've consumed
+ the entire input section. Hopefully we'll get valid info from
+ the other of .debug_frame/.eh_frame. */
+ workaround = FAIL;
+ ret = unit->dwarf_frame_buffer + unit->dwarf_frame_size;
+ break;
+ }
+
+ switch (workaround)
+ {
+ case NONE:
+ break;
+
+ case ALIGN4:
+ complaint (&symfile_complaints,
+ "Corrupt data in %s:%s; align 4 workaround apparently succeeded",
+ unit->dwarf_frame_section->owner->filename,
+ unit->dwarf_frame_section->name);
+ break;
+
+ case ALIGN8:
+ complaint (&symfile_complaints,
+ "Corrupt data in %s:%s; align 8 workaround apparently succeeded",
+ unit->dwarf_frame_section->owner->filename,
+ unit->dwarf_frame_section->name);
+ break;
+
+ default:
+ complaint (&symfile_complaints,
+ "Corrupt data in %s:%s",
+ unit->dwarf_frame_section->owner->filename,
+ unit->dwarf_frame_section->name);
+ break;
+ }
+
+ return ret;
+}
+
\f
/* FIXME: kettenis/20030504: This still needs to be integrated with
unit.dwarf_frame_section = dwarf_eh_frame_section;
/* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
- that for the i386/amd64 target, which currently is the only
- target in GCC that supports/uses the DW_EH_PE_datarel
- encoding. */
+ that for the i386/amd64 target, which currently is the only
+ target in GCC that supports/uses the DW_EH_PE_datarel
+ encoding. */
got = bfd_get_section_by_name (unit.abfd, ".got");
if (got)
unit.dbase = got->vma;
projects / deliverable / binutils-gdb.git / commitdiff
