From b162660d3ac44688f18919cd460423022e467512 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Wed, 1 Mar 2023 11:30:17 -0500 Subject: Avoid fetching one past the end of translate()'s "to" parameter. This is usually harmless, but if you were very unlucky it could provoke a segfault due to the "to" string being right up against the end of memory. Found via valgrind testing (so we might've found it earlier, except that our regression tests lacked any exercise of translate()'s deletion feature). Fix by switching the order of the test-for-end-of-string and advance-pointer steps. While here, compute "to_ptr + tolen" just once. (Smarter compilers might figure that out for themselves, but let's just make sure.) Report and fix by Daniil Anisimov, in bug #17816. Discussion: https://postgr.es/m/17816-70f3d2764e88a108@postgresql.org --- src/backend/utils/adt/oracle_compat.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'src/backend/utils/adt/oracle_compat.c') diff --git a/src/backend/utils/adt/oracle_compat.c b/src/backend/utils/adt/oracle_compat.c index ecd8268b23b..85db92411f0 100644 --- a/src/backend/utils/adt/oracle_compat.c +++ b/src/backend/utils/adt/oracle_compat.c @@ -723,7 +723,8 @@ translate(PG_FUNCTION_ARGS) text *to = PG_GETARG_TEXT_PP(2); text *result; char *from_ptr, - *to_ptr; + *to_ptr, + *to_end; char *source, *target; int m, @@ -745,6 +746,7 @@ translate(PG_FUNCTION_ARGS) from_ptr = VARDATA_ANY(from); tolen = VARSIZE_ANY_EXHDR(to); to_ptr = VARDATA_ANY(to); + to_end = to_ptr + tolen; /* * The worst-case expansion is to substitute a max-length character for a @@ -778,16 +780,16 @@ translate(PG_FUNCTION_ARGS) } if (i < fromlen) { - /* substitute */ + /* substitute, or delete if no corresponding "to" character */ char *p = to_ptr; for (i = 0; i < from_index; i++) { - p += pg_mblen(p); - if (p >= (to_ptr + tolen)) + if (p >= to_end) break; + p += pg_mblen(p); } - if (p < (to_ptr + tolen)) + if (p < to_end) { len = pg_mblen(p); memcpy(target, p, len); -- cgit v1.2.3