[PATCH mm-unstable 0/2] mm/damon/sysfs-schemes: avoid updating

[PATCH mm-unstable 0/2] mm/damon/sysfs-schemes: avoid updating

[SeongJae Park]

A DAMON sysfs interface user can start DAMON with a scheme, remove the
sysfs directory for the scheme, and then ask clears/updates of the
scheme's tried regions.  Because the schemes tried regions clear/update
logic doesn't aware of the situation, it results in an invalid memory
access.  Fix the bugs by checking if the scheme sysfs directory exists.

This patchset is fixing commits in mm-unstable.  Andrew, please meld the
first patch into "mm/damon/sysfs: implement DAMOS tried regions update
command"[1], and the second patch into "mm/damon/sysfs-schemes:
implement DAMOS-tried regions clear command"[2].

[1] https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-sysfs-implement-damos-tried-regions-update-command.patch
[2] https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-sysfs-schemes-implement-damos-tried-regions-clear-command.patch

SeongJae Park (2):
  mm/damon/sysfs-schemes: skip tried regions update if the scheme
    directory has removed
  mm/damon/sysfs-schemes: skip schemes regions clearing if the scheme
    directory has removed

 mm/damon/sysfs-schemes.c | 9 +++++++++
 1 file changed, 9 insertions(+)

-- 
2.25.1

[PATCH mm-unstable 1/2] mm/damon/sysfs-schemes: skip tried regions update if the scheme directory has removed

[SeongJae Park]

A DAMON sysfs interface user can start DAMON with a scheme, remove the
sysfs directory for the scheme, and then ask updates of the scheme's
tried regions.  Because the schemes tried regions update logic doesn't
aware of the situation, it results in an invalid memory access.  Fix the
bug by checking if the scheme sysfs directory exists.

Fixes: 1322c8148dfe ("mm/damon/sysfs: implement DAMOS tried regions update command") # mm-unstable
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index a79aa32d3422..4df3c99983e8 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1231,6 +1231,11 @@ static int damon_sysfs_before_damos_apply(struct damon_ctx *ctx,
 			break;
 		schemes_idx++;
 	}
+
+	/* user could removed the scheme sysfs dir */
+	if (schemes_idx >= sysfs_schemes->nr)
+		return 0;
+
 	sysfs_regions = sysfs_schemes->schemes_arr[schemes_idx]->tried_regions;
 	region = damon_sysfs_scheme_region_alloc(r);
 	list_add_tail(&region->list, &sysfs_regions->regions_list);
-- 
2.25.1

[PATCH mm-unstable 2/2] mm/damon/sysfs-schemes: skip schemes regions clearing if the scheme directory has removed

[SeongJae Park]

A DAMON sysfs interface user can start DAMON with a scheme, remove the
sysfs directory for the scheme, and then ask clearing of the scheme's
tried regions.  Because the schemes tried regions clearing logic doesn't
aware of the situation, it results in an invalid memory access.  Fix the
bug by checking if the scheme sysfs directory exists.

Fixes: bb9641eb3a3e ("mm/damon/sysfs-schemes: implement DAMOS-tried regions clear command") # mm-unstable
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 4df3c99983e8..e6baf55d617d 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1260,6 +1260,10 @@ int damon_sysfs_schemes_clear_regions(
 	damon_for_each_scheme(scheme, ctx) {
 		struct damon_sysfs_scheme *sysfs_scheme;
 
+		/* user could removed the scheme sysfs dir */
+		if (schemes_idx >= sysfs_schemes->nr)
+			break;
+
 		sysfs_scheme = sysfs_schemes->schemes_arr[schemes_idx++];
 		damon_sysfs_scheme_regions_rm_dirs(
 				sysfs_scheme->tried_regions);
-- 
2.25.1