Hi,
oss-fuzz on GDAL has spotted a crashing bug in SQLite:
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=10750 (not accessible
yet)
Here's the way to reproduce it:
$ valgrind ~/install-sqlite-3.25.1/bin/sqlite3 corrupt.db \
"SELECT 1 FROM gpkg_tile_matrix WHERE table_name = 'my' AND \
pixel_x_size > 0 ORDER BY zoom_level DESC"
[...]
==8944== Invalid read of size 1
==8944== at 0x46202C: sqlite3VdbeIdxRowid (sqlite3.c:80107)
==8944== by 0x46C934: sqlite3VdbeExec (sqlite3.c:88086)
==8944== by 0x4634D1: sqlite3Step (sqlite3.c:81035)
==8944== by 0x46371F: sqlite3_step (sqlite3.c:81098)
==8944== by 0x417CD5: exec_prepared_stmt (shell.c:10255)
==8944== by 0x4187CB: shell_exec (shell.c:10523)
==8944== by 0x427918: main (shell.c:16263)
==8944== Address 0x105fe5de7 is not stack'd, malloc'd or (recently) free'd
==8944==
==8944==
==8944== Process terminating with default action of signal 11 (SIGSEGV)
==8944== Access not within mapped region at address 0x105FE5DE7
==8944== at 0x46202C: sqlite3VdbeIdxRowid (sqlite3.c:80107)
==8944== by 0x46C934: sqlite3VdbeExec (sqlite3.c:88086)
==8944== by 0x4634D1: sqlite3Step (sqlite3.c:81035)
==8944== by 0x46371F: sqlite3_step (sqlite3.c:81098)
==8944== by 0x417CD5: exec_prepared_stmt (shell.c:10255)
==8944== by 0x4187CB: shell_exec (shell.c:10523)
==8944== by 0x427918: main (shell.c:16263)
I've come up with this simple patch that fixes the issue (the cast to (int) or
a large unsigned value not fitting on int is undefined behaviour in C)
$ diff -u sqlite3.c.bak sqlite3.c
--- sqlite3.c.bak 2018-09-30 18:43:28.248503877 +0200
+++ sqlite3.c 2018-09-30 18:43:38.520405935 +0200
@@ -80098,7 +80098,7 @@
(void)getVarint32((u8*)m.z, szHdr);
testcase( szHdr==3 );
testcase( szHdr==m.n );
- if( unlikely(szHdr<3 || (int)szHdr>m.n) ){
+ if( unlikely(szHdr<3 || szHdr>(unsigned)m.n) ){
goto idx_rowid_corruption;
}
I can reproduce this on versions at least since sqlite 3.11.0, but I see older
versions have the same faulty code, so this is probably a difference in query
planner behaviour not triggering the bug on that particular query.
Best regards,
Even
--
Spatialys - Geospatial professional services
http://www.spatialys.com
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