Hi, Alexey! On Jan 09, Alexey Botchkov wrote:

revision-id: ce507903d0c (mariadb-10.2.40-161-gce507903d0c) parent(s): 0dae41637ab author: Alexey Botchkov committer: Alexey Botchkov timestamp: 2021-11-22 09:58:46 +0400 message:

MDEV-22742 UBSAN: Many overflow issues in strings/decimal.c - runtime error: signed integer overflow: x * y cannot be represented in type 'long long int' (on optimized builds).

Avoid integer overflow, do the check before the calculation.

diff --git a/strings/decimal.c b/strings/decimal.c index 9d18a9ce52a..6249d7e097a 100644 --- a/strings/decimal.c +++ b/strings/decimal.c @@ -1128,13 +1128,16 @@ int decimal2ulonglong(const decimal_t *from, ulonglong *to)

for (intg=from->intg; intg > 0; intg-=DIG_PER_DEC1) { - ulonglong y=x; - x=x*DIG_BASE + *buf++; - if (unlikely(y > ((ulonglong) ULONGLONG_MAX/DIG_BASE) || x < y)) + if (unlikely ( + x >= ULONGLONG_MAX/DIG_BASE && + (x > ULONGLONG_MAX/DIG_BASE || + *buf > (dec1) (ULONGLONG_MAX%DIG_BASE))))

This took me a while. Personally I find it easier to understand an exclusive condition, like x > ULONGLONG_MAX/DIG_BASE || (x == ULONGLONG_MAX/DIG_BASE && *buf > (dec1) (ULONGLONG_MAX%DIG_BASE)) but it's equivalent to your version, so ok to push. Did you check that this commit fixes all UBSAN issues mentioned in the MDEV-22742? Regards, Sergei VP of MariaDB Server Engineering and security@mariadb.org