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// Copyright (c) Meta Platforms, Inc. and affiliates.
// SPDX-License-Identifier: LGPL-2.1-or-later
static struct drgn_error *parse_vmcoreinfo_u64(const char *value,
const char *newline, int base,
uint64_t *ret)
{
errno = 0;
char *end;
*ret = strtoull(value, &end, base);
if (errno == ERANGE) {
return drgn_error_create(DRGN_ERROR_OVERFLOW,
"number in VMCOREINFO is too large");
} else if (errno || end == value || end != newline) {
return drgn_error_create(DRGN_ERROR_OTHER,
"number in VMCOREINFO is invalid");
}
return NULL;
}
// Linux kernel commit 905415ff3ffb ("lib/buildid: harden build ID parsing
// logic") (in v6.12) contains a bug that results in a garbage build ID in
// VMCOREINFO. It was fixed in the same patch series in commits de3ec364c3c3
// ("lib/buildid: add single folio-based file reader abstraction") and
// d4deb8242341 ("lib/buildid: take into account e_phoff when fetching program
// headers"). However, the broken commit was backported to several stable
// kernels. Some branches were fixed by "lib/buildid: Fix build ID parsing
// logic", but a couple reached their end-of-life while broken. See
// https://lore.kernel.org/all/20241104175256.2327164-1-jolsa@kernel.org/.
//
// The very sad workaround is to ignore the build ID based on a version check.
static void ignore_broken_vmcoreinfo_build_id(struct drgn_program *prog)
{
char *p = (char *)prog->vmcoreinfo.osrelease;
long major = strtol(p, &p, 10), minor = 0, patch = 0;
if (*p == '.') {
minor = strtol(p + 1, &p, 10);
if (*p == '.')
patch = strtol(p + 1, NULL, 10);
}
if ((major == 6 && minor == 11 && patch >= 3 && patch < 10)
|| (major == 6 && minor == 10 && patch >= 14)
|| (major == 6 && minor == 6 && patch >= 55 && patch < 63)
|| (major == 6 && minor == 1 && patch >= 113 && patch < 119)
|| (major == 5 && minor == 15 && patch >= 168))
prog->vmcoreinfo.build_id_len = 0;
}
struct drgn_error *drgn_program_parse_vmcoreinfo(struct drgn_program *prog,
const char *desc,
size_t descsz)
{
struct drgn_error *err;
prog->vmcoreinfo.raw_size = descsz;
prog->vmcoreinfo.raw = memdup(desc, descsz);
if (!prog->vmcoreinfo.raw)
return &drgn_enomem;
for (const char *line = desc, *end = &desc[descsz], *newline;
(newline = memchr(line, '\n', end - line));
line = newline + 1) {
const char *equals = memchr(line, '=', newline - line);
if (!equals)
continue;
const char *value = equals + 1;
@memswitch (line, equals - line)@
@case "BUILD-ID"@
{
size_t build_id_len = (newline - value) / 2;
if (build_id_len > sizeof(prog->vmcoreinfo.build_id)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"BUILD-ID in VMCOREINFO is too long");
}
if (!unhexlify(value, newline - value,
&prog->vmcoreinfo.build_id)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"couldn't parse BUILD-ID in VMCOREINFO");
}
prog->vmcoreinfo.build_id_len = build_id_len;
break;
}
@case "CRASHTIME"@
prog->vmcoreinfo.have_crashtime = true;
break;
@case "OSRELEASE"@
if ((size_t)(newline - value) >=
sizeof(prog->vmcoreinfo.osrelease)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"OSRELEASE in VMCOREINFO is too long");
}
memcpy(prog->vmcoreinfo.osrelease, value,
newline - value);
prog->vmcoreinfo.osrelease[newline - value] = '\0';
break;
@case "PAGESIZE"@
err = parse_vmcoreinfo_u64(value, newline, 0,
&prog->vmcoreinfo.page_size);
if (err)
return err;
break;
@case "KERNELOFFSET"@
err = parse_vmcoreinfo_u64(value, newline, 16,
&prog->vmcoreinfo.kaslr_offset);
if (err)
return err;
break;
@case "SYMBOL(swapper_pg_dir)"@
err = parse_vmcoreinfo_u64(value, newline, 16,
&prog->vmcoreinfo.swapper_pg_dir);
if (err)
return err;
break;
@case "LENGTH(mem_section)"@
err = parse_vmcoreinfo_u64(value, newline, 0,
&prog->vmcoreinfo.mem_section_length);
if (err)
return err;
break;
@case "NUMBER(SECTION_SIZE_BITS)"@
{
uint64_t tmp;
err = parse_vmcoreinfo_u64(value, newline, 0, &tmp);
if (err)
return err;
if (tmp == 0 || tmp > 64) {
return drgn_error_create(DRGN_ERROR_OTHER,
"SECTION_SIZE_BITS in VMCOREINFO is invalid");
}
prog->vmcoreinfo.section_size_bits = tmp;
break;
}
@case "NUMBER(MAX_PHYSMEM_BITS)"@
{
uint64_t tmp;
err = parse_vmcoreinfo_u64(value, newline, 0, &tmp);
if (err)
return err;
if (tmp == 0 || tmp > 64) {
return drgn_error_create(DRGN_ERROR_OTHER,
"MAX_PHYSMEM_BITS in VMCOREINFO is invalid");
}
prog->vmcoreinfo.max_physmem_bits = tmp;
break;
}
@case "NUMBER(pgtable_l5_enabled)"@
{
uint64_t tmp;
err = parse_vmcoreinfo_u64(value, newline, 0, &tmp);
if (err)
return err;
prog->vmcoreinfo.pgtable_l5_enabled = tmp;
break;
}
@case "NUMBER(kimage_voffset)"@
{
err = parse_vmcoreinfo_u64(value, newline, 0,
&prog->vmcoreinfo.kimage_voffset);
if (err)
return err;
break;
}
@case "NUMBER(phys_base)"@
{
err = parse_vmcoreinfo_u64(value, newline, 0,
&prog->vmcoreinfo.phys_base);
if (err)
return err;
prog->vmcoreinfo.have_phys_base = true;
break;
}
@case "NUMBER(KERNELPACMASK)"@
err = parse_vmcoreinfo_u64(value, newline, 16,
&prog->aarch64_insn_pac_mask);
if (err)
return err;
break;
@case "NUMBER(VA_BITS)"@
err = parse_vmcoreinfo_u64(value, newline, 0,
&prog->vmcoreinfo.va_bits);
if (err)
return err;
break;
@case "NUMBER(TCR_EL1_T1SZ)"@
err = parse_vmcoreinfo_u64(value, newline, 0,
&prog->vmcoreinfo.tcr_el1_t1sz);
if (err)
return err;
break;
@case "CONFIG_ARM_LPAE"@
prog->vmcoreinfo.arm_lpae = value[0] == 'y';
break;
@endswitch@
}
if (!prog->vmcoreinfo.osrelease[0]) {
return drgn_error_create(DRGN_ERROR_OTHER,
"VMCOREINFO does not contain valid OSRELEASE");
}
ignore_broken_vmcoreinfo_build_id(prog);
if (!is_power_of_two(prog->vmcoreinfo.page_size)) {
return drgn_error_create(DRGN_ERROR_OTHER,
"VMCOREINFO does not contain valid PAGESIZE");
}
prog->vmcoreinfo.page_shift = ctz(prog->vmcoreinfo.page_size);
if (!prog->vmcoreinfo.swapper_pg_dir) {
return drgn_error_create(DRGN_ERROR_OTHER,
"VMCOREINFO does not contain valid swapper_pg_dir");
}
// Everything else is optional.
return NULL;
}
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