s390/boot: Avoid IPL parameter append past command line

A command line may occupy all but the terminating byte of
COMMAND_LINE_SIZE. In that case append_ipl_block_parm() passes a zero size
to the IPL parameter conversion helpers and points the destination one
byte past early_command_line. The helpers subtract one from the unsigned
size and write the converted parameter outside the command line buffer.

Convert the IPL parameter in the command line parsing buffer first. A
parameter beginning with '=' can then replace the existing command line
regardless of its length, while other parameters are appended only when
space remains.

Fixes: 5ecb2da660ab ("s390: support command lines longer than 896 bytes")
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

0 files changed, 0 insertions, 0 deletions