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| author |   SeongJae Park <sj@kernel.org> | 2022-11-07 16:50:00 +0000 |
|---|---|---|
| committer |   Andrew Morton <akpm@linux-foundation.org> | 2022-11-08 15:57:25 -0800 |
| commit | 1de09a7281edecfdba19b3a07417f6d65243ab5f (patch) | |
| tree | c23ae2757982982d8ce6b67e794df94e5bf5bc18 /mm/damon/dbgfs.c | |
| parent | maple_tree: don't set a new maximum on the node when not reusing nodes (diff) | |
| download | linux-dev-1de09a7281edecfdba19b3a07417f6d65243ab5f.tar.xz linux-dev-1de09a7281edecfdba19b3a07417f6d65243ab5f.zip | |
mm/damon/dbgfs: check if rm_contexts input is for a real context
A user could write a name of a file under 'damon/' debugfs directory,
which is not a user-created context, to 'rm_contexts' file. In the case,
'dbgfs_rm_context()' just assumes it's the valid DAMON context directory
only if a file of the name exist. As a result, invalid memory access
could happen as below. Fix the bug by checking if the given input is for
a directory. This check can filter out non-context inputs because
directories under 'damon/' debugfs directory can be created via only
'mk_contexts' file.
This bug has found by syzbot[1].
[1] https://lore.kernel.org/damon/000000000000ede3ac05ec4abf8e@google.com/
Link: https://lkml.kernel.org/r/20221107165001.5717-2-sj@kernel.org
Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: syzbot+6087eafb76a94c4ac9eb@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org> [5.15.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to '')
| -rw-r--r-- | mm/damon/dbgfs.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c index 6f0ae7d3ae39..b3f454a5c682 100644 --- a/mm/damon/dbgfs.c +++ b/mm/damon/dbgfs.c @@ -890,6 +890,7 @@ out: static int dbgfs_rm_context(char *name) { struct dentry *root, *dir, **new_dirs; + struct inode *inode; struct damon_ctx **new_ctxs; int i, j; int ret = 0; @@ -905,6 +906,12 @@ static int dbgfs_rm_context(char *name) if (!dir) return -ENOENT; + inode = d_inode(dir); + if (!S_ISDIR(inode->i_mode)) { + ret = -EINVAL; + goto out_dput; + } + new_dirs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_dirs), GFP_KERNEL); if (!new_dirs) { |