zfs_log: add flex array fields to log record structs
ZIL log record structs (lr_XX_t) are frequently allocated with extra
space after the struct to carry variable-sized "payload" items.
Linux 6.10+ compiled with CONFIG_FORTIFY_SOURCE has been doing runtime
bounds checking on memcpy() calls. Because these types had no indicator
that they might use more space than their simple definition,
__fortify_memcpy_chk will frequently complain about overruns eg:
memcpy: detected field-spanning write (size 7) of single field
"lr + 1" at zfs_log.c:425 (size 0)
memcpy: detected field-spanning write (size 9) of single field
"(char *)(lr + 1)" at zfs_log.c:593 (size 0)
memcpy: detected field-spanning write (size 4) of single field
"(char *)(lr + 1) + snamesize" at zfs_log.c:594 (size 0)
memcpy: detected field-spanning write (size 7) of single field
"lr + 1" at zfs_log.c:425 (size 0)
memcpy: detected field-spanning write (size 9) of single field
"(char *)(lr + 1)" at zfs_log.c:593 (size 0)
memcpy: detected field-spanning write (size 4) of single field
"(char *)(lr + 1) + snamesize" at zfs_log.c:594 (size 0)
memcpy: detected field-spanning write (size 7) of single field
"lr + 1" at zfs_log.c:425 (size 0)
memcpy: detected field-spanning write (size 9) of single field
"(char *)(lr + 1)" at zfs_log.c:593 (size 0)
memcpy: detected field-spanning write (size 4) of single field
"(char *)(lr + 1) + snamesize" at zfs_log.c:594 (size 0)To fix this, this commit adds flex array fields to all lr_XX_t structs
that require them, and then uses those fields to access that
end-of-struct area rather than more complicated casts and pointer
addition.
Sponsored-by: https://despairlabs.com/sponsor/
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes #16501
Closes #16539