From: Junrui Luo Date: Sat, 7 Mar 2026 07:21:08 +0000 (+0800) Subject: ocfs2/dlm: validate qr_numregions in dlm_match_regions() X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7ab3fbb01bc6d79091bc375e5235d360cd9b78be;p=thirdparty%2Fkernel%2Fstable.git ocfs2/dlm: validate qr_numregions in dlm_match_regions() Patch series "ocfs2/dlm: fix two bugs in dlm_match_regions()". In dlm_match_regions(), the qr_numregions field from a DLM_QUERY_REGION network message is used to drive loops over the qr_regions buffer without sufficient validation. This series fixes two issues: - Patch 1 adds a bounds check to reject messages where qr_numregions exceeds O2NM_MAX_REGIONS. The o2net layer only validates message byte length; it does not constrain field values, so a crafted message can set qr_numregions up to 255 and trigger out-of-bounds reads past the 1024-byte qr_regions buffer. - Patch 2 fixes an off-by-one in the local-vs-remote comparison loop, which uses '<=' instead of '<', reading one entry past the valid range even when qr_numregions is within bounds. This patch (of 2): The qr_numregions field from a DLM_QUERY_REGION network message is used directly as loop bounds in dlm_match_regions() without checking against O2NM_MAX_REGIONS. Since qr_regions is sized for at most O2NM_MAX_REGIONS (32) entries, a crafted message with qr_numregions > 32 causes out-of-bounds reads past the qr_regions buffer. Add a bounds check for qr_numregions before entering the loops. Link: https://lkml.kernel.org/r/SYBPR01MB7881A334D02ACEE5E0645801AF7BA@SYBPR01MB7881.ausprd01.prod.outlook.com Link: https://lkml.kernel.org/r/SYBPR01MB788166F524AD04E262E174BEAF7BA@SYBPR01MB7881.ausprd01.prod.outlook.com Fixes: ea2034416b54 ("ocfs2/dlm: Add message DLM_QUERY_REGION") Signed-off-by: Junrui Luo Reported-by: Yuhao Jiang Reviewed-by: Joseph Qi Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Changwei Ge Cc: Jun Piao Cc: Heming Zhao Signed-off-by: Andrew Morton --- diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c index 70ca79e4bdc3..0a28cb5ded2a 100644 --- a/fs/ocfs2/dlm/dlmdomain.c +++ b/fs/ocfs2/dlm/dlmdomain.c @@ -980,6 +980,14 @@ static int dlm_match_regions(struct dlm_ctxt *dlm, goto bail; } + if (qr->qr_numregions > O2NM_MAX_REGIONS) { + mlog(ML_ERROR, "Domain %s: Joining node %d has invalid " + "number of heartbeat regions %u\n", + qr->qr_domain, qr->qr_node, qr->qr_numregions); + status = -EINVAL; + goto bail; + } + r = remote; for (i = 0; i < qr->qr_numregions; ++i) { mlog(0, "Region %.*s\n", O2HB_MAX_REGION_NAME_LEN, r);