upstream/haproxy
1
0
Fork 0
mirror of https://github.com/haproxy/haproxy.git synced 2026-05-27 20:02:17 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions 16

BUG/MINOR: qpack: fix sign bit mask in qpack_decode_fs_pfx()

Browse source 
The sign bit of the Delta Base integer encoding was extracted using
mask 0x8 (bit 3) instead of 0x80 (bit 7). This was likely a copy-paste
error from other QPACK instructions using 3-bit varints.

According to RFC 9204 Section 5.2.1, for prefix instructions, the sign
bit 'S' is the most significant bit (bit 7) of the first byte, followed
by a 7-bit varint.

This fix is harmless for current HTTP/3 traffic: per RFC 9204, the Delta
Base calculation is strictly used for dynamic table entry references.
Since HAProxy's QPACK dynamic table is currently disabled and the extracted
sign bit is not yet used in the decoding logic (only in debug prints),
this code path has no impact on production for now.

Must be backported to all versions.
This commit is contained in:
Frederic Lecaille 2026-05-27 16:40:52 +02:00
parent 0e83b7cd08
commit e2d2f67666
1 changed files with 1 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
src/qpack-dec.c
View file

@ -239,7 +239,7 @@ static int qpack_decode_fs_pfx(uint64_t *enc_ric, uint64_t *db, int *sign_bit,
return -QPACK_RET_TRUNCATED;
/* Safe access to the sign bit thanks to the check above */
*sign_bit = **raw & 0x8;
*sign_bit = **raw & 0x80;
*db = qpack_get_varint(raw, len, 7);
if (*len == (uint64_t)-1)
return -QPACK_RET_DB;