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author | Bob Peterson <rpeterso@redhat.com> | 2016-06-09 22:24:07 +0300 |
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committer | Bob Peterson <rpeterso@redhat.com> | 2016-06-10 15:01:58 +0300 |
commit | 36e4ad0316c017d5b271378ed9a1c9a4b77fab5f (patch) | |
tree | 4a23a5f7ef511ce6b366c98cc0605bcb91985cb6 /fs/gfs2/main.c | |
parent | 29567292c0b5b2fb484125c280a2175141fe2205 (diff) | |
download | linux-36e4ad0316c017d5b271378ed9a1c9a4b77fab5f.tar.xz |
GFS2: don't set rgrp gl_object until it's inserted into rgrp tree
Before this patch, function read_rindex_entry would set a rgrp
glock's gl_object pointer to itself before inserting the rgrp into
the rgrp rbtree. The problem is: if another process was also reading
the rgrp in, and had already inserted its newly created rgrp, then
the second call to read_rindex_entry would overwrite that value,
then return a bad return code to the caller. Later, other functions
would reference the now-freed rgrp memory by way of gl_object.
In some cases, that could result in gfs2_rgrp_brelse being called
twice for the same rgrp: once for the failed attempt and once for
the "real" rgrp release. Eventually the kernel would panic.
There are also a number of other things that could go wrong when
a kernel module is accessing freed storage. For example, this could
result in rgrp corruption because the fake rgrp would point to a
fake bitmap in memory too, causing gfs2_inplace_reserve to search
some random memory for free blocks, and find some, since we were
never setting rgd->rd_bits to NULL before freeing it.
This patch fixes the problem by not setting gl_object until we
have successfully inserted the rgrp into the rbtree. Also, it sets
rd_bits to NULL as it frees them, which will ensure any accidental
access to the wrong rgrp will result in a kernel panic rather than
file system corruption, which is preferred.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Diffstat (limited to 'fs/gfs2/main.c')
0 files changed, 0 insertions, 0 deletions