rdelaage/postgresql
1
0
Fork 0
mirror of https://git.postgresql.org/git/postgresql.git synced 2024-09-28 00:11:53 +02:00
Code Issues Packages Projects Releases Wiki Activity

Improve pglz_decompress's defenses against corrupt compressed data.

Browse Source 
When processing a match tag, check to see if the claimed "off"
is more than the distance back to the output buffer start.
If it is, then the data is corrupt, and what's more we would
fetch from outside the buffer boundaries and potentially incur
a SIGSEGV.  (Although the odds of that seem relatively low, given
that "off" can't be more than 4K.)

Back-patch to v13; before that, this function wasn't really
trying to protect against bad data.

Report and fix by Flavien Guedez.

Discussion: https://postgr.es/m/01fc0593-e31e-463d-902c-dd43174acee2@oopacity.net
This commit is contained in:
Tom Lane 2023-10-18 20:43:17 -04:00
parent 0a8b7d5c11
commit 2c63dc0356
1 changed files with 8 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
src/common/pg_lzcompress.c
View File

@ -735,11 +735,15 @@ pglz_decompress(const char *source, int32 slen, char *dest,
/*
* Check for corrupt data: if we fell off the end of the
* source, or if we obtained off = 0, we have problems. (We
* must check this, else we risk an infinite loop below in the
* face of corrupt data.)
* source, or if we obtained off = 0, or if off is more than
* the distance back to the buffer start, we have problems.
* (We must check for off = 0, else we risk an infinite loop
* below in the face of corrupt data. Likewise, the upper
* limit on off prevents accessing outside the buffer
* boundaries.)
*/
if (unlikely(sp > srcend || off == 0))
if (unlikely(sp > srcend || off == 0 ||
off > (dp - (unsigned char *) dest)))
return -1;
/*