[PATCH 1/2] crypto: return -ENOSPC on compression destination overflow

[Suseendran Bhaskaran]

In the acomp/scomp compression interface, callers pass a bounded
destination buffer and rely on the return code to distinguish a
destination buffer overflow (incompressible input) from genuine
compressor failures (such as invalid parameters, uninitialized state, or
hardware errors).

While the multi-segment streaming path in zstd_compress(),
crypto/deflate.c, and lib/842/842_compress.c returns -ENOSPC when the
destination buffer runs out of space, the single-buffer path
zstd_compress_one() (taken when input and output are contiguous single
pages, such as in zswap) as well as lz4, lz4hc, lzo, and lzo-rle return
-EINVAL instead of -ENOSPC on destination buffer overflow.

For users such as zswap, which reduced its per-CPU compression buffer to
a single page in commit 0b1bf60c324a ("mm/zswap: reduce the size of the
compression buffer to a single page"), incompressible pages typically
overflow the PAGE_SIZE destination buffer due to compressor header/token
overhead. Because these compressors return -EINVAL rather than -ENOSPC,
zswap cannot distinguish a destination buffer overflow from a compressor
failure, causing broken debugfs error accounting (reject_compress_fail
vs. reject_compress_poor) or masking real compressor errors.

Update zstd_compress_one(), lz4, lz4hc, lzo, and lzo-rle to return
-ENOSPC when the compressed output overflows the destination buffer,
matching the streaming path in zstd_compress(), deflate, and 842.

Fixes: f5ad93ffb541 ("crypto: zstd - convert to acomp")
Signed-off-by: Suseendran Bhaskaran <suseendranb@xxxxxxxxxx>
---
 crypto/lz4.c     | 2 +-
 crypto/lz4hc.c   | 2 +-
 crypto/lzo-rle.c | 2 +-
 crypto/lzo.c     | 2 +-
 crypto/zstd.c    | 5 ++++-
 5 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/crypto/lz4.c b/crypto/lz4.c
index 57b713516aef..c37e29afc831 100644
--- a/crypto/lz4.c
+++ b/crypto/lz4.c
@@ -35,7 +35,7 @@ static int __lz4_compress_crypto(const u8 *src, unsigned int slen,
 		slen, *dlen, ctx);
 
 	if (!out_len)
-		return -EINVAL;
+		return -ENOSPC;
 
 	*dlen = out_len;
 	return 0;
diff --git a/crypto/lz4hc.c b/crypto/lz4hc.c
index bb84f8a68cb5..3098466eb72a 100644
--- a/crypto/lz4hc.c
+++ b/crypto/lz4hc.c
@@ -33,7 +33,7 @@ static int __lz4hc_compress_crypto(const u8 *src, unsigned int slen,
 		*dlen, LZ4HC_DEFAULT_CLEVEL, ctx);
 
 	if (!out_len)
-		return -EINVAL;
+		return -ENOSPC;
 
 	*dlen = out_len;
 	return 0;
diff --git a/crypto/lzo-rle.c b/crypto/lzo-rle.c
index 794e7ec49536..483327873efd 100644
--- a/crypto/lzo-rle.c
+++ b/crypto/lzo-rle.c
@@ -34,7 +34,7 @@ static int __lzorle_compress(const u8 *src, unsigned int slen,
 	err = lzorle1x_1_compress_safe(src, slen, dst, &tmp_len, ctx);
 
 	if (err != LZO_E_OK)
-		return -EINVAL;
+		return err == LZO_E_OUTPUT_OVERRUN ? -ENOSPC : -EINVAL;
 
 	*dlen = tmp_len;
 	return 0;
diff --git a/crypto/lzo.c b/crypto/lzo.c
index d43242b24b4e..378b491b0cbd 100644
--- a/crypto/lzo.c
+++ b/crypto/lzo.c
@@ -34,7 +34,7 @@ static int __lzo_compress(const u8 *src, unsigned int slen,
 	err = lzo1x_1_compress_safe(src, slen, dst, &tmp_len, ctx);
 
 	if (err != LZO_E_OK)
-		return -EINVAL;
+		return err == LZO_E_OUTPUT_OVERRUN ? -ENOSPC : -EINVAL;
 
 	*dlen = tmp_len;
 	return 0;
diff --git a/crypto/zstd.c b/crypto/zstd.c
index 556f5d2bdd5f..7fafbdc19fd9 100644
--- a/crypto/zstd.c
+++ b/crypto/zstd.c
@@ -86,8 +86,11 @@ static int zstd_compress_one(struct acomp_req *req, struct zstd_ctx *ctx,
 
 	out_len = zstd_compress_cctx(ctx->cctx, dst, req->dlen, src, req->slen,
 				     &ctx->params);
-	if (zstd_is_error(out_len))
+	if (zstd_is_error(out_len)) {
+		if (zstd_get_error_code(out_len) == ZSTD_error_dstSize_tooSmall)
+			return -ENOSPC;
 		return -EINVAL;
+	}
 
 	*dlen = out_len;
 
-- 
2.56.0.218.g1ec904b173-goog