Le lun. 24 août 2020 à 20:11, Nick Terrell <terrelln@xxxxxx> a écrit
:
On Aug 21, 2020, at 9:29 AM, Paul Cercueil <paul@xxxxxxxxxxxxxxx>
wrote:
The zstd decompression code, as it is right now, will have internal
values overflow on 32-bit systems when the output size is LONG_MAX.
Until someone smarter than me can figure out how to fix the zstd
code
properly, limit the destination buffer size to 512 MiB, which
should be
enough for everybody, in order to make it usable on 32-bit systems.
Can you bump the size up to 2GB? I suspect the problem inside of zstd
is an off-by-one error or something similar, so getting closer to the
limit
shouldn't be a problem. I’d feel more comfortable with 2GB, since
kernels can get pretty large.
SZ_1G is the biggest I can go to get the kernel to boot. With SZ_2G it
won't boot.
Hmm, zstd shouldn’t be overflowing that value. I’m currently
preparing
a patch to updating the version of zstd in the kernel, and using
upstream
directly. I will add a test upstream in 32-bit mode to ensure that we
don’t
overflow a 32-bit size_t, so this will be fixed after the update.
Great, thanks.
Cheers,
-Paul
-Nick
Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
---
lib/decompress_unzstd.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/lib/decompress_unzstd.c b/lib/decompress_unzstd.c
index 0ad2c15479ed..e1c03b1eaa6e 100644
--- a/lib/decompress_unzstd.c
+++ b/lib/decompress_unzstd.c
@@ -77,6 +77,7 @@
#include <linux/decompress/mm.h>
#include <linux/kernel.h>
+#include <linux/sizes.h>
#include <linux/zstd.h>
/* 128MB is the maximum window size supported by zstd. */
@@ -179,7 +180,7 @@ static int INIT __unzstd(unsigned char *in_buf,
long in_len,
size_t ret;
if (out_len == 0)
- out_len = LONG_MAX; /* no limit */
+ out_len = SZ_512M; /* should be big enough, right? */
if (fill == NULL && flush == NULL)
/*
--
2.28.0
