The normalization pass in the sorting routine of the relative exception
table serves two purposes:
- it ensures that the address fields of the exception table entries are
fully ordered, so that no ambiguities arise between entries with
identical instruction offsets (i.e., when two instructions that are
exactly 8 bytes apart each have an exception table entry associated with
them)
- it ensures that the offsets of both the instruction and the fixup fields
of each entry are relative to their final location after sorting.
Commit eb608fb366 ("s390/exceptions: switch to relative exception table
entries") ported the relative exception table format from x86, but modified
the sorting routine to only normalize the instruction offset field and not
the fixup offset field. The result is that the fixup offset of each entry
will be relative to the original location of the entry before sorting,
likely leading to crashes when those entries are dereferenced.
Fixes: eb608fb366 ("s390/exceptions: switch to relative exception table entries")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This is the s390 port of 70627654 "x86, extable: Switch to relative
exception table entries".
Reduces the size of our exception tables by 50% on 64 bit builds.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
