From: Nick Terrell <terrelln@xxxxxx> Bump the ZO_z_extra_bytes margin for zstd. Zstd needs 3 bytes per 128 KB, and has a 22 byte fixed overhead. Zstd needs to maintain 128 KB of space at all times, since that is the maximum block size. See the comments regarding in-place decompression added in lib/decompress_unzstd.c for details. The existing code is written so that all the compression algorithms use the same ZO_z_extra_bytes. It is taken to be the maximum of the growth rate plus the maximum fixed overhead. The comments just above this diff state that: Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx> Signed-off-by: Nick Terrell <terrelln@xxxxxx> --- arch/x86/boot/header.S | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S index 735ad7f21ab0..6dbd7e9f74c9 100644 --- a/arch/x86/boot/header.S +++ b/arch/x86/boot/header.S @@ -539,8 +539,14 @@ pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr # the size-dependent part now grows so fast. # # extra_bytes = (uncompressed_size >> 8) + 65536 +# +# ZSTD compressed data grows by at most 3 bytes per 128K, and only has a 22 +# byte fixed overhead but has a maximum block size of 128K, so it needs a +# larger margin. +# +# extra_bytes = (uncompressed_size >> 8) + 131072 -#define ZO_z_extra_bytes ((ZO_z_output_len >> 8) + 65536) +#define ZO_z_extra_bytes ((ZO_z_output_len >> 8) + 131072) #if ZO_z_output_len > ZO_z_input_len # define ZO_z_extract_offset (ZO_z_output_len + ZO_z_extra_bytes - \ ZO_z_input_len) -- 2.27.0
