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authorSeongJae Park <sj@kernel.org>2022-11-07 16:50:00 +0000
committerAndrew Morton <akpm@linux-foundation.org>2022-11-08 15:57:25 -0800
commit1de09a7281edecfdba19b3a07417f6d65243ab5f (patch)
treec23ae2757982982d8ce6b67e794df94e5bf5bc18 /mm
parent7dc5ba6254bb242a9f45e43549171a2d84d25e6a (diff)
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 'mm')
-rw-r--r--mm/damon/dbgfs.c7
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) {