| Bug #31566 | my_write(fd, 0x0, 0, flags) fails with EFAULT on some platforms | ||
|---|---|---|---|
| Submitted: | 12 Oct 2007 14:23 | Modified: | 20 Dec 2007 0:38 |
| Reporter: | Axel Schwenke | Email Updates: | |
| Status: | Closed | Impact on me: | |
| Category: | MySQL Server | Severity: | S1 (Critical) |
| Version: | 5.0.46 | OS: | Linux ( ) |
| Assigned to: | Alexey Kopytov | CPU Architecture: | Any |
| Tags: | bfsm_2007_10_18 | ||
| Triage: | D2 (Serious) | ||
[12 Oct 2007 15:50]
Konstantin Osipov
Chad, please treat this as a community contribution.
[15 Oct 2007 15:45]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/35578 ChangeSet@1.2535, 2007-10-15 19:44:58+04:00, kaa@polly.(none) +1 -0 Fix for bug #31566: my_write(fd, 0x0, 0, flags) fails with EFAULT on some platforms Since the behavior of write(fd, buf, 0) is undefined, it may fail with EFAULT on some architectures when buf == NULL. The error was propagated up to a caller, since my_write() code did not handle it properly. Fixed by checking the 'number of bytes' argument in my_write() and returning before calling the write() system call when there is nothing to write.
[24 Oct 2007 17:16]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/36287 ChangeSet@1.2535, 2007-10-24 21:16:20+04:00, kaa@polly.(none) +1 -0 Fix for bug #31566: my_write(fd, 0x0, 0, flags) fails with EFAULT on some platforms Since the behavior of write(fd, buf, 0) is undefined, it may fail with EFAULT on some architectures when buf == NULL. The error was propagated up to a caller, since my_write() code did not handle it properly. Fixed by checking the 'number of bytes' argument in my_write() and returning before calling the write() system call when there is nothing to write.
[25 Oct 2007 4:57]
Bugs System
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from: http://lists.mysql.com/commits/36317 ChangeSet@1.2551, 2007-10-25 08:19:57+04:00, kaa@polly.(none) +1 -0 Replaced 'return' with DBUG_RETURN() in the fix for bug #31566.
[7 Dec 2007 23:08]
Bugs System
Pushed into 6.0.5-alpha
[7 Dec 2007 23:09]
Bugs System
Pushed into 5.1.23-rc
[7 Dec 2007 23:10]
Bugs System
Pushed into 5.0.54
[20 Dec 2007 0:38]
Paul Dubois
Noted in 5.0.54, 5.1.23, 6.0.5 changelogs. The internal my_write() function was made more robust against non-portable behavior of the write() system call for a buffer length of 0.
Description: MySQL did not install on a Debian/Mips64 platform. Also the test suite failed in bootstrap phase with error message: /root/nn/mysql-5.0.46/sql/mysqld --no-defaults --bootstrap --basedir=/root/nn/mysql-5.0.46/mysql-test --datadir=/root/nn/mysql-5.0.46/mysql-test/var/master-data --skip-innodb --skip-ndbcluster --tmpdir=. --core-file --language=/root/nn/mysql-5.0.46/sql/share/english --character-sets-dir=/root/nn/mysql-5.0.46/sql/share/charsets ERROR: 1051 Unknown table 'db' 071009 9:21:04 [ERROR] Aborting 071009 9:21:04 [Note] /root/nn/mysql-5.0.46/sql/mysqld: Shutdown complete Running mysqld with trace log enabled showed this: T@32771: | | | | | | <make_empty_rec T@32771: | | | | | | >my_write T@32771: | | | | | | | my: Fd: 6 Buffer: 0x7f5fed90 Count: 2 MyFlags: 4 T@32771: | | | | | | <my_write T@32771: | | | | | | >my_write T@32771: | | | | | | | my: Fd: 6 Buffer: 0x0 Count: 0 MyFlags: 4 T@32771: | | | | | | | error: Write only -1 bytes, error: 14 T@32771: | | | | | | <my_write the failed my_write() translates to line 180 in unireg.cc (function mysql_create_frm) The same my_write() works on Linux i686 and x86_64. Seems the write(2) system call on mips64 checks the buffer address even when length==0 and returns EFAULT when the buffer is at 0x0. How to repeat: Try to run MySQL on the mips64 platform. Suggested fix: In my_write() test if Count==0 and return immediately in this case. --- my_write.c.bak 2007-07-19 23:37:06.000000000 +0200 +++ my_write.c 2007-10-12 16:05:39.000000000 +0200 @@ -29,6 +29,9 @@ Filedes, (long) Buffer, Count, MyFlags)); errors=0; written=0L; + if (Count == 0) + DBUG_RETURN(0); /* nothing to write */ + for (;;) { if ((writenbytes = (uint) write(Filedes, Buffer, Count)) == Count)