From: Ryan Lee Date: Thu, 1 May 2025 19:54:38 +0000 (-0700) Subject: apparmor: ensure WB_HISTORY_SIZE value is a power of 2 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6c055e62560b958354625604293652753d82bcae;p=thirdparty%2Fkernel%2Flinux.git apparmor: ensure WB_HISTORY_SIZE value is a power of 2 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 --- diff --git a/security/apparmor/include/match.h b/security/apparmor/include/match.h index 01a703fef8e18..21e049b408246 100644 --- a/security/apparmor/include/match.h +++ b/security/apparmor/include/match.h @@ -137,7 +137,8 @@ aa_state_t aa_dfa_matchn_until(struct aa_dfa *dfa, aa_state_t 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 f2d9c57f87943..1ceabde550f2c 100644 --- a/security/apparmor/match.c +++ b/security/apparmor/match.c @@ -681,6 +681,7 @@ aa_state_t aa_dfa_matchn_until(struct aa_dfa *dfa, aa_state_t 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)