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H A D | dm-flakey.c | diff f50714b57aecb6b3dc81d578e295f86d9c73f078 Sun Jan 22 13:02:57 CST 2023 Mikulas Patocka <mpatocka@redhat.com> dm flakey: don't corrupt the zero page
When we need to zero some range on a block device, the function __blkdev_issue_zero_pages submits a write bio with the bio vector pointing to the zero page. If we use dm-flakey with corrupt bio writes option, it will corrupt the content of the zero page which results in crashes of various userspace programs. Glibc assumes that memory returned by mmap is zeroed and it uses it for calloc implementation; if the newly mapped memory is not zeroed, calloc will return non-zeroed memory.
Fix this bug by testing if the page is equal to ZERO_PAGE(0) and avoiding the corruption in this case.
Cc: stable@vger.kernel.org Fixes: a00f5276e266 ("dm flakey: Properly corrupt multi-page bios.") Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
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