[PATCH] crypto: zstd - Fix compression bug caused by truncation

[Herbert Xu]

On Mon, Sep 29, 2025 at 11:51:36PM +0000, Han Xu wrote:
> Hi Suman,
> 
> The patch f5ad93ffb5411 "crypto: zstd - convert to acomp"
> leads to the following kernel dump during UBIFS write back.

Thanks for the detailed report and instructions!

Please let me know if you still get the crash with this patch:

---8<---
Use size_t for the return value of zstd_compress_cctx as otherwise
negative errors will be truncated to a positive value.

Reported-by: Han Xu <han.xu at nxp.com>
Fixes: f5ad93ffb541 ("crypto: zstd - convert to acomp")
Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>

diff --git a/crypto/zstd.c b/crypto/zstd.c
index c2a19cb0879d..ac318d333b68 100644
--- a/crypto/zstd.c
+++ b/crypto/zstd.c
@@ -83,7 +83,7 @@ static void zstd_exit(struct crypto_acomp *acomp_tfm)
 static int zstd_compress_one(struct acomp_req *req, struct zstd_ctx *ctx,
 			     const void *src, void *dst, unsigned int *dlen)
 {
-	unsigned int out_len;
+	size_t out_len;
 
 	ctx->cctx = zstd_init_cctx(ctx->wksp, ctx->wksp_size);
 	if (!ctx->cctx)
-- 
Email: Herbert Xu <herbert at gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt