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| author | Theodore Ts'o <tytso@mit.edu> | 2018-04-18 17:49:31 +0200 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2018-04-18 17:49:31 +0200 |
| commit | b2569260d55228b617bd82aba6d0db2faeeb4116 (patch) | |
| tree | 45069307616ca3dc612cca1425de5a1f0b9647be /fs/jbd2 | |
| parent | ext4: prevent right-shifting extents beyond EXT_MAX_BLOCKS (diff) | |
| download | linux-b2569260d55228b617bd82aba6d0db2faeeb4116.tar.xz linux-b2569260d55228b617bd82aba6d0db2faeeb4116.zip | |
ext4: set h_journal if there is a failure starting a reserved handle
If ext4 tries to start a reserved handle via
jbd2_journal_start_reserved(), and the journal has been aborted, this
can result in a NULL pointer dereference. This is because the fields
h_journal and h_transaction in the handle structure share the same
memory, via a union, so jbd2_journal_start_reserved() will clear
h_journal before calling start_this_handle(). If this function fails
due to an aborted handle, h_journal will still be NULL, and the call
to jbd2_journal_free_reserved() will pass a NULL journal to
sub_reserve_credits().
This can be reproduced by running "kvm-xfstests -c dioread_nolock
generic/475".
Cc: stable@kernel.org # 3.11
Fixes: 8f7d89f36829b ("jbd2: transaction reservation support")
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'fs/jbd2')
| -rw-r--r-- | fs/jbd2/transaction.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index ac311037d7a5..8aa453784402 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -532,6 +532,7 @@ int jbd2_journal_start_reserved(handle_t *handle, unsigned int type, */ ret = start_this_handle(journal, handle, GFP_NOFS); if (ret < 0) { + handle->h_journal = journal; jbd2_journal_free_reserved(handle); return ret; } |