From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E357C311C32; Sat, 21 Mar 2026 18:28:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774117702; cv=none; b=u2X9JPOdThDEoRB0yQwzIfT6rgXWYo2aya24C8uXmQk7g5L7tbfAbxp0ei7jezFDKDaTKfMN6H5pZwl45Q4TLN5z0tG4qy4MaymBIBpS5Dt3csI8Sd9V8yXvISSqVbim4ZfCfU7RElyF7YJjfQUrazzRrlt4tl43BCDVWDQQOiI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774117702; c=relaxed/simple; bh=oBID60Mn8tY5owzZdEfs3uUWxHGjP8bqVh4u8vKqC1I=; h=Date:To:From:Subject:Message-Id; b=hG6ZzTsZoPhGGI7t/38PmyoIbM3BgfjjaFVheU5jh0QNDKewUQquecClJOntFLSiVP+2UDfM6kFXQW28MWI5gdo2nBelTeSUVKrjRSYDDkT9QtcPbq9FxFwFfF5uQVN/zxF9P3E9zYgupUdujLm5sK+rKM0audg5B5W3m3n/5IA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=O3agV0h3; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="O3agV0h3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73CDBC19421; Sat, 21 Mar 2026 18:28:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1774117701; bh=oBID60Mn8tY5owzZdEfs3uUWxHGjP8bqVh4u8vKqC1I=; h=Date:To:From:Subject:From; b=O3agV0h3ecRj2P+HasF1y7uR5K03DzEIiUylmwqosLEYdRXKrea1tdCFqlDxJHgTu qEssKGq2QZQJvrMgxKYjZOlFpJJDE6SDIXU5Ct1LKqK9wgle6KsyRDy+vwgmsHmfUj VGrCTtluhZs9Zd3tcCN4oe9a+bUd6QReR9r13UTM= Date: Sat, 21 Mar 2026 11:28:20 -0700 To: mm-commits@vger.kernel.org,stable@vger.kernel.org,sj@kernel.org,objecting@objecting.org,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-damon-sysfs-check-contexts-nr-in-repeat_call_fn.patch added to mm-hotfixes-unstable branch Message-Id: <20260321182821.73CDBC19421@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/damon/sysfs: check contexts->nr in repeat_call_fn has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-damon-sysfs-check-contexts-nr-in-repeat_call_fn.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-sysfs-check-contexts-nr-in-repeat_call_fn.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Josh Law Subject: mm/damon/sysfs: check contexts->nr in repeat_call_fn Date: Sat, 21 Mar 2026 10:54:26 -0700 damon_sysfs_repeat_call_fn() calls damon_sysfs_upd_tuned_intervals(), damon_sysfs_upd_schemes_stats(), and damon_sysfs_upd_schemes_effective_quotas() without checking contexts->nr. If nr_contexts is set to 0 via sysfs while DAMON is running, these functions dereference contexts_arr[0] and cause a NULL pointer dereference. Add the missing check. For example, the issue can be reproduced using DAMON sysfs interface and DAMON user-space tool (damo) [1] like below. $ sudo damo start --refresh_interval 1s $ echo 0 | sudo tee \ /sys/kernel/mm/damon/admin/kdamonds/0/contexts/nr_contexts Link: https://patch.msgid.link/20260320163559.178101-3-objecting@objecting.org Link: https://lkml.kernel.org/r/20260321175427.86000-4-sj@kernel.org Link: https://github.com/damonitor/damo [1] Fixes: d809a7c64ba8 ("mm/damon/sysfs: implement refresh_ms file internal work") Signed-off-by: Josh Law Reviewed-by: SeongJae Park Signed-off-by: SeongJae Park Cc: [6.17+] Signed-off-by: Andrew Morton --- mm/damon/sysfs.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/damon/sysfs.c~mm-damon-sysfs-check-contexts-nr-in-repeat_call_fn +++ a/mm/damon/sysfs.c @@ -1620,9 +1620,12 @@ static int damon_sysfs_repeat_call_fn(vo if (!mutex_trylock(&damon_sysfs_lock)) return 0; + if (sysfs_kdamond->contexts->nr != 1) + goto out; damon_sysfs_upd_tuned_intervals(sysfs_kdamond); damon_sysfs_upd_schemes_stats(sysfs_kdamond); damon_sysfs_upd_schemes_effective_quotas(sysfs_kdamond); +out: mutex_unlock(&damon_sysfs_lock); return 0; } _ Patches currently in -mm which might be from objecting@objecting.org are mm-damon-sysfs-fix-param_ctx-leak-on-damon_sysfs_new_test_ctx-failure.patch mm-damon-sysfs-check-contexts-nr-before-accessing-contexts_arr.patch mm-damon-sysfs-check-contexts-nr-in-repeat_call_fn.patch lib-maple_tree-fix-swapped-arguments-in-mas_safe_pivot-call.patch mm-damon-core-document-damos_commit_dests-failure-semantics.patch lib-glob-fix-grammar-and-replace-non-inclusive-terminology.patch lib-glob-add-explicit-include-for-exporth.patch lib-glob-replace-bitwise-or-with-logical-operation-on-boolean.patch lib-glob-clean-up-bool-abuse-in-pointer-arithmetic.patch lib-uuid-fix-typo-reversion-to-revision-in-comment.patch lib-inflate-fix-memory-leak-in-inflate_fixed-on-inflate_codes-failure.patch lib-inflate-fix-memory-leak-in-inflate_dynamic-on-inflate_codes-failure.patch lib-inflate-fix-grammar-in-comment-variable-to-variables.patch lib-inflate-fix-typo-this-results-to-the-results-in-comment.patch lib-bug-fix-inconsistent-capitalization-in-bug-message.patch lib-bug-remove-unnecessary-variable-initializations.patch lib-idr-fix-ida_find_first_range-missing-ids-across-chunk-boundaries.patch lib-decompress_bunzip2-fix-32-bit-shift-undefined-behavior.patch lib-ts_bm-fix-integer-overflow-in-pattern-length-calculation.patch lib-ts_kmp-fix-integer-overflow-in-pattern-length-calculation.patch lib-glob-initialize-back_str-to-silence-uninitialized-variable-warning.patch lib-bch-fix-signed-left-shift-undefined-behavior.patch lib-bch-fix-signed-shift-overflow-in-build_mod8_tables.patch