From eda378a0abdf8d7e25a6a542f6f00dd281501613 Mon Sep 17 00:00:00 2001 From: Ryan Lee Date: Thu, 1 May 2025 12:54:38 -0700 Subject: apparmor: ensure WB_HISTORY_SIZE value is a power of 2 [ Upstream commit 6c055e62560b958354625604293652753d82bcae ] WB_HISTORY_SIZE was defined to be a value not a power of 2, despite a comment in the declaration of struct match_workbuf stating it is and a modular arithmetic usage in the inc_wb_pos macro assuming that it is. Bump WB_HISTORY_SIZE's value up to 32 and add a BUILD_BUG_ON_NOT_POWER_OF_2 line to ensure that any future changes to the value of WB_HISTORY_SIZE respect this requirement. Fixes: 136db994852a ("apparmor: increase left match history buffer size") Signed-off-by: Ryan Lee Signed-off-by: John Johansen Signed-off-by: Sasha Levin --- security/apparmor/include/match.h | 3 ++- security/apparmor/match.c | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) (limited to 'security') diff --git a/security/apparmor/include/match.h b/security/apparmor/include/match.h index 884489590588..29306ec87fd1 100644 --- a/security/apparmor/include/match.h +++ b/security/apparmor/include/match.h @@ -141,7 +141,8 @@ unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start, void aa_dfa_free_kref(struct kref *kref); -#define WB_HISTORY_SIZE 24 +/* This needs to be a power of 2 */ +#define WB_HISTORY_SIZE 32 struct match_workbuf { unsigned int count; unsigned int pos; diff --git a/security/apparmor/match.c b/security/apparmor/match.c index 3e9e1eaf990e..0e683ee323e3 100644 --- a/security/apparmor/match.c +++ b/security/apparmor/match.c @@ -672,6 +672,7 @@ unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start, #define inc_wb_pos(wb) \ do { \ + BUILD_BUG_ON_NOT_POWER_OF_2(WB_HISTORY_SIZE); \ wb->pos = (wb->pos + 1) & (WB_HISTORY_SIZE - 1); \ wb->len = (wb->len + 1) & (WB_HISTORY_SIZE - 1); \ } while (0) -- cgit v1.2.3