Hello Suman Kumar Chakraborty,
Commit f5ad93ffb541 ("crypto: zstd - convert to acomp") from Jun 16,
2025 (linux-next), leads to the following Smatch static checker
warning:
crypto/zstd.c:273 zstd_decompress()
warn: duplicate check 'scur' (previous on line 235)
crypto/zstd.c
208 static int zstd_decompress(struct acomp_req *req)
209 {
210 struct crypto_acomp_stream *s;
211 unsigned int total_out = 0;
212 unsigned int scur, dcur;
213 zstd_out_buffer outbuf;
214 struct acomp_walk walk;
215 zstd_in_buffer inbuf;
216 struct zstd_ctx *ctx;
217 size_t pending_bytes;
218 int ret;
219
220 s = crypto_acomp_lock_stream_bh(&zstd_streams);
221 ctx = s->ctx;
222
223 ret = acomp_walk_virt(&walk, req, true);
224 if (ret)
225 goto out;
226
227 ctx->dctx = zstd_init_dstream(ZSTD_MAX_SIZE, ctx->wksp, ctx->wksp_size);
228 if (!ctx->dctx) {
229 ret = -EINVAL;
230 goto out;
231 }
232
233 do {
234 scur = acomp_walk_next_src(&walk);
235 if (scur) {
236 inbuf.pos = 0;
237 inbuf.size = scur;
238 inbuf.src = walk.src.virt.addr;
239 } else {
240 break;
If scur is NULL then we break.
241 }
242
243 do {
244 dcur = acomp_walk_next_dst(&walk);
245 if (dcur == req->dlen && scur == req->slen) {
246 ret = zstd_decompress_one(req, ctx, walk.src.virt.addr,
247 walk.dst.virt.addr, &total_out);
248 acomp_walk_done_dst(&walk, dcur);
249 acomp_walk_done_src(&walk, scur);
250 goto out;
251 }
252
253 if (!dcur) {
254 ret = -ENOSPC;
255 goto out;
256 }
257
258 outbuf.pos = 0;
259 outbuf.dst = (u8 *)walk.dst.virt.addr;
260 outbuf.size = dcur;
261
262 pending_bytes = zstd_decompress_stream(ctx->dctx, &outbuf, &inbuf);
263 if (ZSTD_isError(pending_bytes)) {
264 ret = -EIO;
265 goto out;
266 }
267
268 total_out += outbuf.pos;
269
270 acomp_walk_done_dst(&walk, outbuf.pos);
271 } while (scur != inbuf.pos);
272
--> 273 if (scur)
No need to check. It's weird that the line before is
} while (scur != inbuf.pos); instead of } while (inbuf.pos != scur);
Normally, the variable goes first.
274 acomp_walk_done_src(&walk, scur);
275 } while (ret == 0);
276
277 out:
278 if (ret)
279 req->dlen = 0;
280 else
281 req->dlen = total_out;
282
283 crypto_acomp_unlock_stream_bh(s);
284
285 return ret;
286 }
regards,
dan carpenter
