s390 fixes for 6.2-rc7
- With CONFIG_VMAP_STACK enabled it is not possible to load the s390
specific diag288_wdt watchdog module. Reason is that a pointer to a
string is passed to an inline assembly; this string however is located on
the stack, while the instruction within the inline assembly expects a
physicial address. Fix this by copying the string to a kmalloc'ed buffer.
- The diag288_wdt watchdog module does not indicate that it accesses memory
from an inline assembly, which it does. Add "memory" to the clobber list
to prevent the compiler from optimizing code incorrectly away.
- Pass size of the uncompressed kernel image to __decompress() call.
Otherwise the kernel image decompressor may corrupt/overwrite an
initrd. This was reported to happen on s390 after commit 2aa14b1ab2c4
("zstd: import usptream v1.5.2").
s390/decompressor: specify __decompress() buf len to avoid overflow
Historically calls to __decompress() didn't specify "out_len" parameter
on many architectures including s390, expecting that no writes beyond
uncompressed kernel image are performed. This has changed since commit
2aa14b1ab2c4 ("zstd: import usptream v1.5.2") which includes zstd library
commit 6a7ede3dfccb ("Reduce size of dctx by reutilizing dst buffer
(#2751)"). Now zstd decompression code might store literal buffer in
the unwritten portion of the destination buffer. Since "out_len" is
not set, it is considered to be unlimited and hence free to use for
optimization needs. On s390 this might corrupt initrd or ipl report
which are often placed right after the decompressor buffer. Luckily the
size of uncompressed kernel image is already known to the decompressor,
so to avoid the problem simply specify it in the "out_len" parameter.
Link: https://github.com/facebook/zstd/commit/6a7ede3dfccb
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Tested-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Link: https://lore.kernel.org/r/patch-1.thread-41c676.git-41c676c2d153.your-ad-here.call-01675030179-ext-9637@work.hours
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
1 file changed
