Hello Amir Goldstein,
The patch 7ba39960c7f3: "fanotify: support reporting non-decodeable
file handles" from May 2, 2023, leads to the following Smatch static
checker warning:
fs/notify/fanotify/fanotify.c:451 fanotify_encode_fh()
warn: assigning signed to unsigned: 'fh->type = type' 's32min-(-1),1-254,256-s32max'
(unpublished garbage Smatch check).
fs/notify/fanotify/fanotify.c
403 static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
404 unsigned int fh_len, unsigned int *hash,
405 gfp_t gfp)
406 {
407 int dwords, type = 0;
408 char *ext_buf = NULL;
409 void *buf = fh->buf;
410 int err;
411
412 fh->type = FILEID_ROOT;
413 fh->len = 0;
414 fh->flags = 0;
415
416 /*
417 * Invalid FHs are used by FAN_FS_ERROR for errors not
418 * linked to any inode. The f_handle won't be reported
419 * back to userspace.
420 */
421 if (!inode)
422 goto out;
423
424 /*
425 * !gpf means preallocated variable size fh, but fh_len could
426 * be zero in that case if encoding fh len failed.
427 */
428 err = -ENOENT;
429 if (fh_len < 4 || WARN_ON_ONCE(fh_len % 4) || fh_len > MAX_HANDLE_SZ)
430 goto out_err;
431
432 /* No external buffer in a variable size allocated fh */
433 if (gfp && fh_len > FANOTIFY_INLINE_FH_LEN) {
434 /* Treat failure to allocate fh as failure to encode fh */
435 err = -ENOMEM;
436 ext_buf = kmalloc(fh_len, gfp);
437 if (!ext_buf)
438 goto out_err;
439
440 *fanotify_fh_ext_buf_ptr(fh) = ext_buf;
441 buf = ext_buf;
442 fh->flags |= FANOTIFY_FH_FLAG_EXT_BUF;
443 }
444
445 dwords = fh_len >> 2;
446 type = exportfs_encode_fid(inode, buf, &dwords);
447 err = -EINVAL;
448 if (!type || type == FILEID_INVALID || fh_len != dwords << 2)
exportfs_encode_fid() can return negative errors. Do we need to check
if (!type etc?
449 goto out_err;
450
--> 451 fh->type = type;
452 fh->len = fh_len;
453
454 out:
455 /*
456 * Mix fh into event merge key. Hash might be NULL in case of
457 * unhashed FID events (i.e. FAN_FS_ERROR).
458 */
459 if (hash)
460 *hash ^= fanotify_hash_fh(fh);
461
462 return FANOTIFY_FH_HDR_LEN + fh_len;
463
464 out_err:
465 pr_warn_ratelimited("fanotify: failed to encode fid (type=%d, len=%d, err=%i)\n",
466 type, fh_len, err);
467 kfree(ext_buf);
468 *fanotify_fh_ext_buf_ptr(fh) = NULL;
469 /* Report the event without a file identifier on encode error */
470 fh->type = FILEID_INVALID;
471 fh->len = 0;
472 return 0;
473 }
regards,
dan carpenter
