s390/boot: Avoid IPL parameter append past command line

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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: 5ecb2da660 ("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>

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Vasily Gorbik 2026-08-19 12:30:33 +02:00 • committed by Heiko Carstens

parent a0c798ed41

commit d76181dfab

1 changed files with 12 additions and 14 deletions

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arch/s390/boot/ipl_parm.c

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