From e9c6a182649f4259db704ae15a91ac820e63b0ca Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 16 Oct 2013 03:17:47 +0100 Subject: [PATCH] dm snapshot: fix data corruption This patch fixes a particular type of data corruption that has been encountered when loading a snapshot's metadata from disk. When we allocate a new chunk in persistent_prepare, we increment ps->next_free and we make sure that it doesn't point to a metadata area by further incrementing it if necessary. When we load metadata from disk on device activation, ps->next_free is positioned after the last used data chunk. However, if this last used data chunk is followed by a metadata area, ps->next_free is positioned erroneously to the metadata area. A newly-allocated chunk is placed at the same location as the metadata area, resulting in data or metadata corruption. This patch changes the code so that ps->next_free skips the metadata area when metadata are loaded in function read_exceptions. The patch also moves a piece of code from persistent_prepare_exception to a separate function skip_metadata to avoid code duplication. CVE-2013-4299 Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Cc: Mike Snitzer Signed-off-by: Alasdair G Kergon --- Reading git-format-patch failed