From: Mikulas Patocka Date: Fri, 1 Mar 2013 22:45:44 +0000 (+0000) Subject: dm: fix truncated status strings X-Git-Tag: v3.2.41~64 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4c8e681cfb1ce38e5c335ea943acc19be49bb302;p=pandora-kernel.git dm: fix truncated status strings commit fd7c092e711ebab55b2688d3859d95dfd0301f73 upstream. Avoid returning a truncated table or status string instead of setting the DM_BUFFER_FULL_FLAG when the last target of a table fills the buffer. When processing a table or status request, the function retrieve_status calls ti->type->status. If ti->type->status returns non-zero, retrieve_status assumes that the buffer overflowed and sets DM_BUFFER_FULL_FLAG. However, targets don't return non-zero values from their status method on overflow. Most targets returns always zero. If a buffer overflow happens in a target that is not the last in the table, it gets noticed during the next iteration of the loop in retrieve_status; but if a buffer overflow happens in the last target, it goes unnoticed and erroneously truncated data is returned. In the current code, the targets behave in the following way: * dm-crypt returns -ENOMEM if there is not enough space to store the key, but it returns 0 on all other overflows. * dm-thin returns errors from the status method if a disk error happened. This is incorrect because retrieve_status doesn't check the error code, it assumes that all non-zero values mean buffer overflow. * all the other targets always return 0. This patch changes the ti->type->status function to return void (because most targets don't use the return code). Overflow is detected in retrieve_status: if the status method fills up the remaining space completely, it is assumed that buffer overflow happened. Signed-off-by: Mikulas Patocka Signed-off-by: Alasdair G Kergon [bwh: Backported to 3.2: - Adjust context - dm_status_fn doesn't take a status_flags parameter - Bump the last component of each current version (verified not to match any version used in mainline) - Drop changes to dm-verity] Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed