diff options
author | Jean Delvare <jdelvare@suse.de> | 2015-03-20 04:59:47 -0400 |
---|---|---|
committer | Matt Fleming <matt.fleming@intel.com> | 2015-03-27 06:53:46 -0400 |
commit | bfbaafae8519d82d10da6abe75f5766dd5b20475 (patch) | |
tree | d876c1735a8ea9718a3c6f5e122d5aee91547812 | |
parent | 6d9ff473317245e3e5cd9922b4520411c2296388 (diff) |
firmware: dmi_scan: Prevent dmi_num integer overflow
dmi_num is a u16, dmi_len is a u32, so this construct:
dmi_num = dmi_len / 4;
would result in an integer overflow for a DMI table larger than
256 kB. I've never see such a large table so far, but SMBIOS 3.0
makes it possible so maybe we'll see such tables in the future.
So instead of faking a structure count when the entry point does
not provide it, adjust the loop condition in dmi_table() to properly
deal with the case where dmi_num is not set.
This bug was introduced with the initial SMBIOS 3.0 support in commit
fc43026278b2 ("dmi: add support for SMBIOS 3.0 64-bit entry point").
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Cc: <stable@vger.kernel.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
-rw-r--r-- | drivers/firmware/dmi_scan.c | 22 |
1 files changed, 7 insertions, 15 deletions
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c index 69fac068669f..2eebd28b4c40 100644 --- a/drivers/firmware/dmi_scan.c +++ b/drivers/firmware/dmi_scan.c | |||
@@ -86,10 +86,13 @@ static void dmi_table(u8 *buf, u32 len, int num, | |||
86 | int i = 0; | 86 | int i = 0; |
87 | 87 | ||
88 | /* | 88 | /* |
89 | * Stop when we see all the items the table claimed to have | 89 | * Stop when we have seen all the items the table claimed to have |
90 | * OR we run off the end of the table (also happens) | 90 | * (SMBIOS < 3.0 only) OR we reach an end-of-table marker OR we run |
91 | * off the end of the table (should never happen but sometimes does | ||
92 | * on bogus implementations.) | ||
91 | */ | 93 | */ |
92 | while ((i < num) && (data - buf + sizeof(struct dmi_header)) <= len) { | 94 | while ((!num || i < num) && |
95 | (data - buf + sizeof(struct dmi_header)) <= len) { | ||
93 | const struct dmi_header *dm = (const struct dmi_header *)data; | 96 | const struct dmi_header *dm = (const struct dmi_header *)data; |
94 | 97 | ||
95 | /* | 98 | /* |
@@ -529,21 +532,10 @@ static int __init dmi_smbios3_present(const u8 *buf) | |||
529 | if (memcmp(buf, "_SM3_", 5) == 0 && | 532 | if (memcmp(buf, "_SM3_", 5) == 0 && |
530 | buf[6] < 32 && dmi_checksum(buf, buf[6])) { | 533 | buf[6] < 32 && dmi_checksum(buf, buf[6])) { |
531 | dmi_ver = get_unaligned_be16(buf + 7); | 534 | dmi_ver = get_unaligned_be16(buf + 7); |
535 | dmi_num = 0; /* No longer specified */ | ||
532 | dmi_len = get_unaligned_le32(buf + 12); | 536 | dmi_len = get_unaligned_le32(buf + 12); |
533 | dmi_base = get_unaligned_le64(buf + 16); | 537 | dmi_base = get_unaligned_le64(buf + 16); |
534 | 538 | ||
535 | /* | ||
536 | * The 64-bit SMBIOS 3.0 entry point no longer has a field | ||
537 | * containing the number of structures present in the table. | ||
538 | * Instead, it defines the table size as a maximum size, and | ||
539 | * relies on the end-of-table structure type (#127) to be used | ||
540 | * to signal the end of the table. | ||
541 | * So let's define dmi_num as an upper bound as well: each | ||
542 | * structure has a 4 byte header, so dmi_len / 4 is an upper | ||
543 | * bound for the number of structures in the table. | ||
544 | */ | ||
545 | dmi_num = dmi_len / 4; | ||
546 | |||
547 | if (dmi_walk_early(dmi_decode) == 0) { | 539 | if (dmi_walk_early(dmi_decode) == 0) { |
548 | pr_info("SMBIOS %d.%d present.\n", | 540 | pr_info("SMBIOS %d.%d present.\n", |
549 | dmi_ver >> 8, dmi_ver & 0xFF); | 541 | dmi_ver >> 8, dmi_ver & 0xFF); |