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| author | David Goulet <dgoulet@torproject.org> | 2020-01-14 12:42:09 -0500 |
|---|---|---|
| committer | Nick Mathewson <nickm@torproject.org> | 2020-01-21 10:31:29 -0500 |
| commit | 780e498f760b139fb540d2e050de08df60714f4a (patch) | |
| tree | 338f232b5c164d665bc5b643afd709f0a038c985 /src/feature | |
| parent | 02f1caa583ca0e09e4c75ff6d9399f5d53931d2b (diff) | |
| download | tor-780e498f760b139fb540d2e050de08df60714f4a.tar.gz tor-780e498f760b139fb540d2e050de08df60714f4a.zip | |
hs-v3: Code improvement for INTRO2 MAC validation
Pointed by nickm during the review of #32709.
Signed-off-by: David Goulet <dgoulet@torproject.org>
Diffstat (limited to 'src/feature')
| -rw-r--r-- | src/feature/hs/hs_cell.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/src/feature/hs/hs_cell.c b/src/feature/hs/hs_cell.c index 680897cf90..021a41825d 100644 --- a/src/feature/hs/hs_cell.c +++ b/src/feature/hs/hs_cell.c @@ -776,6 +776,12 @@ get_introduce2_keys_and_verify_mac(hs_cell_introduce2_data_t *data, * in the cell is at the end of the encrypted section. */ { uint8_t mac[DIGEST256_LEN]; + + /* Make sure we are now about to underflow. */ + if (encrypted_section_len < sizeof(mac)) { + goto err; + } + /* The MAC field is at the very end of the ENCRYPTED section. */ size_t mac_offset = encrypted_section_len - sizeof(mac); /* Compute the MAC. Use the entire encoded payload with a length up to the @@ -785,7 +791,7 @@ get_introduce2_keys_and_verify_mac(hs_cell_introduce2_data_t *data, encrypted_section, encrypted_section_len, intro_keys->mac_key, sizeof(intro_keys->mac_key), mac, sizeof(mac)); - if (tor_memcmp(mac, encrypted_section + mac_offset, sizeof(mac))) { + if (tor_memneq(mac, encrypted_section + mac_offset, sizeof(mac))) { log_info(LD_REND, "Invalid MAC validation for INTRODUCE2 cell"); goto err; } |