From: Hung-Te Lin hungte@chromium.org
commit 4b708b7b1a2c09fbdfff6b942ebe3a160213aacd upstream.
The VPD implementation from Chromium Vital Product Data project used to parse data from untrusted input without checking if the meta data is invalid or corrupted. For example, the size from decoded content may be negative value, or larger than whole input buffer. Such invalid data may cause buffer overflow.
To fix that, the size parameters passed to vpd_decode functions should be changed to unsigned integer (u32) type, and the parsing of entry header should be refactored so every size field is correctly verified before starting to decode.
Fixes: ad2ac9d5c5e0 ("firmware: Google VPD: import lib_vpd source files") Signed-off-by: Hung-Te Lin hungte@chromium.org Cc: stable stable@vger.kernel.org Reviewed-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Stephen Boyd swboyd@chromium.org Link: https://lore.kernel.org/r/20190830022402.214442-1-hungte@chromium.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/firmware/google/vpd.c | 4 +- drivers/firmware/google/vpd_decode.c | 55 ++++++++++++++++++++--------------- drivers/firmware/google/vpd_decode.h | 6 +-- 3 files changed, 37 insertions(+), 28 deletions(-)
--- a/drivers/firmware/google/vpd.c +++ b/drivers/firmware/google/vpd.c @@ -92,8 +92,8 @@ static int vpd_section_check_key_name(co return VPD_OK; }
-static int vpd_section_attrib_add(const u8 *key, s32 key_len, - const u8 *value, s32 value_len, +static int vpd_section_attrib_add(const u8 *key, u32 key_len, + const u8 *value, u32 value_len, void *arg) { int ret; --- a/drivers/firmware/google/vpd_decode.c +++ b/drivers/firmware/google/vpd_decode.c @@ -11,8 +11,8 @@
#include "vpd_decode.h"
-static int vpd_decode_len(const s32 max_len, const u8 *in, - s32 *length, s32 *decoded_len) +static int vpd_decode_len(const u32 max_len, const u8 *in, + u32 *length, u32 *decoded_len) { u8 more; int i = 0; @@ -32,18 +32,39 @@ static int vpd_decode_len(const s32 max_ } while (more);
*decoded_len = i; + return VPD_OK; +} + +static int vpd_decode_entry(const u32 max_len, const u8 *input_buf, + u32 *_consumed, const u8 **entry, u32 *entry_len) +{ + u32 decoded_len; + u32 consumed = *_consumed;
+ if (vpd_decode_len(max_len - consumed, &input_buf[consumed], + entry_len, &decoded_len) != VPD_OK) + return VPD_FAIL; + if (max_len - consumed < decoded_len) + return VPD_FAIL; + + consumed += decoded_len; + *entry = input_buf + consumed; + + /* entry_len is untrusted data and must be checked again. */ + if (max_len - consumed < *entry_len) + return VPD_FAIL; + + consumed += decoded_len; + *_consumed = consumed; return VPD_OK; }
-int vpd_decode_string(const s32 max_len, const u8 *input_buf, s32 *consumed, +int vpd_decode_string(const u32 max_len, const u8 *input_buf, u32 *consumed, vpd_decode_callback callback, void *callback_arg) { int type; - int res; - s32 key_len; - s32 value_len; - s32 decoded_len; + u32 key_len; + u32 value_len; const u8 *key; const u8 *value;
@@ -58,26 +79,14 @@ int vpd_decode_string(const s32 max_len, case VPD_TYPE_STRING: (*consumed)++;
- /* key */ - res = vpd_decode_len(max_len - *consumed, &input_buf[*consumed], - &key_len, &decoded_len); - if (res != VPD_OK || *consumed + decoded_len >= max_len) + if (vpd_decode_entry(max_len, input_buf, consumed, &key, + &key_len) != VPD_OK) return VPD_FAIL;
- *consumed += decoded_len; - key = &input_buf[*consumed]; - *consumed += key_len; - - /* value */ - res = vpd_decode_len(max_len - *consumed, &input_buf[*consumed], - &value_len, &decoded_len); - if (res != VPD_OK || *consumed + decoded_len > max_len) + if (vpd_decode_entry(max_len, input_buf, consumed, &value, + &value_len) != VPD_OK) return VPD_FAIL;
- *consumed += decoded_len; - value = &input_buf[*consumed]; - *consumed += value_len; - if (type == VPD_TYPE_STRING) return callback(key, key_len, value, value_len, callback_arg); --- a/drivers/firmware/google/vpd_decode.h +++ b/drivers/firmware/google/vpd_decode.h @@ -25,8 +25,8 @@ enum { };
/* Callback for vpd_decode_string to invoke. */ -typedef int vpd_decode_callback(const u8 *key, s32 key_len, - const u8 *value, s32 value_len, +typedef int vpd_decode_callback(const u8 *key, u32 key_len, + const u8 *value, u32 value_len, void *arg);
/* @@ -44,7 +44,7 @@ typedef int vpd_decode_callback(const u8 * If one entry is successfully decoded, sends it to callback and returns the * result. */ -int vpd_decode_string(const s32 max_len, const u8 *input_buf, s32 *consumed, +int vpd_decode_string(const u32 max_len, const u8 *input_buf, u32 *consumed, vpd_decode_callback callback, void *callback_arg);
#endif /* __VPD_DECODE_H */