diff options
| author | David Howells <dhowells@redhat.com> | 2026-05-12 13:33:47 +0100 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2026-05-12 14:42:30 +0200 |
| commit | 0ef37eef83fad3542ee06db2940433ae1a92b39d (patch) | |
| tree | 3a5ee8975247fba7c74182f98f384d7d19849d76 | |
| parent | 0aad5704c6b4d14007d4eab15883e8524e4310f4 (diff) | |
netfs: Fix overrun check in netfs_extract_user_iter()
Fix netfs_extract_user_iter() so that if iov_iter_extract_pages() overfills
pages[], then those pages don't get included in the iterator constructed at
the end of the function. If there was an overfill, memory corruption has
already happened.
Fixes: 85dd2c8ff368 ("netfs: Add a function to extract a UBUF or IOVEC into a BVEC iterator")
Closes: https://sashiko.dev/#/patchset/20260427154639.180684-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260512123404.719402-11-dhowells@redhat.com
cc: Paulo Alcantara <pc@manguebit.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
| -rw-r--r-- | fs/netfs/iterator.c | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/fs/netfs/iterator.c b/fs/netfs/iterator.c index 429e4396e1b0..b375567e0520 100644 --- a/fs/netfs/iterator.c +++ b/fs/netfs/iterator.c @@ -72,21 +72,24 @@ ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len, break; } - if (ret > count) { - pr_err("get_pages rc=%zd more than %zu\n", ret, count); + if (WARN(ret > count, + "%s: extract_pages overrun %zd > %zu bytes\n", + __func__, ret, count)) { + ret = -EIO; break; } - count -= ret; - ret += offset; - cur_npages = DIV_ROUND_UP(ret, PAGE_SIZE); - - if (npages + cur_npages > max_pages) { - pr_err("Out of bvec array capacity (%u vs %u)\n", - npages + cur_npages, max_pages); + cur_npages = DIV_ROUND_UP(offset + ret, PAGE_SIZE); + if (WARN(cur_npages > max_pages - npages, + "%s: extract_pages overrun %u > %u pages\n", + __func__, npages + cur_npages, max_pages)) { + ret = -EIO; break; } + count -= ret; + ret += offset; + for (i = 0; i < cur_npages; i++) { len = ret > PAGE_SIZE ? PAGE_SIZE : ret; bvec_set_page(bv + npages + i, *pages++, len - offset, offset); @@ -97,6 +100,11 @@ ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len, npages += cur_npages; } + /* Note: Don't try to clean up after EIO. Either we got no pages, so + * nothing to clean up, or we got a buffer overrun, memory corruption + * and can't trust the stuff in the buffer (a WARN was emitted). + */ + if (ret < 0 && (ret == -ENOMEM || npages == 0)) { for (i = 0; i < npages; i++) unpin_user_page(bv[i].bv_page); |