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libdrgn: orc_info: check ORC section alignment instead of copying

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In practice, the .orc_unwind and .orc_unwind_ip sections will always be
suitably aligned. Check it, then assume the alignment later.

Signed-off-by: Omar Sandoval <osandov@osandov.com>
This commit is contained in:
Omar Sandoval 2023-06-20 22:11:26 -07:00
parent 8526b86644
commit 0bb503c6a0
1 changed files with 15 additions and 11 deletions
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26
libdrgn/orc_info.c
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@ -3,6 +3,7 @@
#include <byteswap.h>
#include <gelf.h>
#include <stdalign.h>
#include <stdlib.h>
#include <string.h>
@ -25,10 +26,8 @@ void drgn_module_orc_info_deinit(struct drgn_module *module)
*/
static inline uint64_t drgn_raw_orc_pc(struct drgn_module *module, size_t i)
{
int32_t offset;
memcpy(&offset,
(int32_t *)module->debug_file->scn_data[DRGN_SCN_ORC_UNWIND_IP]->d_buf + i,
sizeof(offset));
int32_t offset =
((int32_t *)module->debug_file->scn_data[DRGN_SCN_ORC_UNWIND_IP]->d_buf)[i];
if (drgn_elf_file_bswap(module->debug_file))
offset = bswap_32(offset);
return module->orc.pc_base + UINT64_C(4) * i + offset;
@ -54,9 +53,8 @@ static int compare_orc_entries(const void *a, const void *b)
*/
const struct drgn_orc_entry *entries =
module->debug_file->scn_data[DRGN_SCN_ORC_UNWIND]->d_buf;
uint16_t flags_a, flags_b;
memcpy(&flags_a, &entries[index_a].flags, sizeof(flags_a));
memcpy(&flags_b, &entries[index_b].flags, sizeof(flags_b));
uint16_t flags_a = entries[index_a].flags;
uint16_t flags_b = entries[index_b].flags;
if (drgn_elf_file_bswap(module->debug_file)) {
flags_a = bswap_16(flags_a);
flags_b = bswap_16(flags_b);
@ -208,6 +206,14 @@ static struct drgn_error *drgn_debug_info_parse_orc(struct drgn_module *module)
}
if (!num_entries)
return NULL;
if ((uintptr_t)orc_unwind_ip->d_buf % alignof(int32_t) != 0) {
return drgn_error_create(DRGN_ERROR_OTHER,
".orc_unwind_ip is not sufficiently aligned");
}
if ((uintptr_t)orc_unwind->d_buf % alignof(struct drgn_orc_entry) != 0) {
return drgn_error_create(DRGN_ERROR_OTHER,
".orc_unwind is not sufficiently aligned");
}
size_t *indices = malloc_array(num_entries, sizeof(indices[0]));
if (!indices)
@ -249,10 +255,8 @@ static struct drgn_error *drgn_debug_info_parse_orc(struct drgn_module *module)
bool bswap = drgn_elf_file_bswap(module->debug_file);
for (size_t i = 0; i < num_entries; i++) {
size_t index = indices[i];
int32_t offset;
memcpy(&offset, &orig_offsets[index], sizeof(offset));
struct drgn_orc_entry entry;
memcpy(&entry, &orig_entries[index], sizeof(entry));
int32_t offset = orig_offsets[index];
struct drgn_orc_entry entry = orig_entries[index];
if (bswap) {
offset = bswap_32(offset);
entry.sp_offset = bswap_16(entry.sp_offset);