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CKI Backport Bot
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JIRA: https://redhat.atlassian.net/browse/RHEL-240184 CVE: CVE-2026-68145 Backported from tree(s): linux commit 9c7d8f7c8994c790fca501dc45ce66e7356cbe05 Author: Zhang Yi <yi.zhang@huawei.com> Date: Tue Jul 14 16:23:24 2026 +0800 iomap: fix out-of-bounds bitmap_set() with zero-length range ifs_set_range_dirty() and ifs_set_range_uptodate() compute last_blk as (off + len - 1) >> i_blkbits. When off is 0 and len is 0, the unsigned subtraction underflows to SIZE_MAX, producing a huge last_blk and nr_blks value that causes bitmap_set() to write far beyond the ifs->state allocation. Regarding ifs_set_range_uptodate(), it is temporarily safe because len cannot be passed in as 0. However, for ifs_set_range_dirty() this is reachable from __iomap_write_end(): when copy_folio_from_iter_atomic() returns 0 (e.g. user buffer fault) and the folio is already uptodate, the guard at the top of __iomap_write_end() does not trigger because !folio_test_uptodate() is false, and iomap_set_range_dirty() is called with copied == 0. Add a !len guard to both functions before the computation, so that a zero-length range is a no-op. Fixes: 4ce02c679722 ("iomap: Add per-block dirty state tracking to improve performance") Cc: stable@vger.kernel.org # v6.6 Signed-off-by: Zhang Yi <yi.zhang@huawei.com> Link: https://patch.msgid.link/20260714082325.325163-5-yi.zhang@huaweicloud.com Reviewed-by: Joanne Koong <joannelkoong@gmail.com> Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org> (cherry picked from commit 9c7d8f7c8994c790fca501dc45ce66e7356cbe05) Assisted-by: Patchpal Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>