Tested with valgrind and no issue
. As I can't run MSAN and I don't see any obvious issues with the code, there is not much that I can do here 
I also find a bit strange that there could be any issues as there are checksums for rows and data
and if there would be any wrong transformations the checksums should notice that.
hm..
If can you find out where in myisampack.test things fail (in other words which myisampack command was executed) then I could just run that myisampack command under valgrind and check what could be wrong.
I tried the following patch:
diff --git a/mysql-test/main/myisampack.test b/mysql-test/main/myisampack.test
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index 1f97a28e6fd..ecd4c371b21 100644
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--- a/mysql-test/main/myisampack.test
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+++ b/mysql-test/main/myisampack.test
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@@ -31,7 +31,9 @@ INSERT INTO t1 VALUES
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FLUSH TABLES;
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let $MYSQLD_DATADIR= `select @@datadir`;
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--exec $MYISAMPACK -s $MYSQLD_DATADIR/test/t1
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---exec $MYISAMCHK -srq $MYSQLD_DATADIR/test/t1
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+--echo exec $MYISAMCHK -srq $MYSQLD_DATADIR/test/t1
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+sleep 3600;
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+
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--exec $MYISAMCHK -s --unpack $MYSQLD_DATADIR/test/t1
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CHECK TABLE t1 EXTENDED;
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DROP TABLE t1;
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diff --git a/storage/myisam/mi_packrec.c b/storage/myisam/mi_packrec.c
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index d5bfdac3008..43481e03f43 100644
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--- a/storage/myisam/mi_packrec.c
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+++ b/storage/myisam/mi_packrec.c
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@@ -1188,7 +1188,7 @@ static void decode_bytes(MI_COLUMNDEF *rec,MI_BIT_BUFF *bit_buff,uchar *to,
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static void decode_bytes(MI_COLUMNDEF *rec, MI_BIT_BUFF *bit_buff, uchar *to,
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uchar *end)
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{
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- reg1 uint bits,low_byte;
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+ uint bits,low_byte;
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reg3 uint16 *pos;
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reg4 uint table_bits,table_and;
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MI_DECODE_TREE *decode_tree;
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@@ -1233,7 +1233,9 @@ static void decode_bytes(MI_COLUMNDEF *rec, MI_BIT_BUFF *bit_buff, uchar *to,
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}
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/* First use info in quick_table */
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low_byte=(bit_buff->current_byte >> (bits - table_bits)) & table_and;
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+ __msan_check_mem_is_initialized(&low_byte, sizeof low_byte);
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low_byte=decode_tree->table[low_byte];
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+ __msan_check_mem_is_initialized(&low_byte, sizeof low_byte);
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if (low_byte & IS_CHAR)
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{
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*to++ = (low_byte & 255); /* Found char in quick table */ |
You may want to use VALGRIND_CHECK_MEM_IS_DEFINED() instead.
The first invocation will report that low_byte is uninitialized. gdb seems to confirm that even without a need to invoke __msan_dump_shadow():
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10.5 6df2f2db11bf0a559db54e18315ad37e6a4d5573 |
Program received signal SIGABRT, Aborted.
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__GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
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50 ../sysdeps/unix/sysv/linux/raise.c: Tiedostoa tai hakemistoa ei ole.
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(gdb) up 5
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#5 0x00005555556fcd58 in decode_bytes (rec=<optimized out>,
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bit_buff=0x7fffffffd820, to=0x7070000000d2 '\245' <repeats 14 times>,
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end=0x7070000000d3 '\245' <repeats 13 times>)
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at /mariadb/10.5m/storage/myisam/mi_packrec.c:1236
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1236 __msan_check_mem_is_initialized(&low_byte, sizeof low_byte);
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(gdb) p *bit_buff
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$1 = {current_byte = 3785729445, bits = 8,
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pos = 0x707000000149 "\245\245\245\245\245\245\245",
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end = 0x707000000146 "\245\245\245\245\245\245\245\245\245\245",
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blob_pos = 0x0, blob_end = 0x0, error = 0}
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Fixed in my 10.5 tree, will be pushed shortly together with other changes
Fix pushed into 10.5.4
This was not user visible issue as the huffman code lookup tables would automatically ignore any of the uninitialised bits
Fixed by adding a end-zero byte to the bit-stream buffer.