From 9d8ec0b5b5295bd23d979d1b2b905de25c36fff2 Mon Sep 17 00:00:00 2001 From: Zijing Yin Date: Thu, 15 Oct 2026 06:31:57 -0700 Subject: [PATCH] wifi: cfg80211: fix out-of-bounds read in valid_rule() valid_rule() validates a struct fwdb_rule from the regulatory database firmware file, but bounds checks only the first byte of the structure, the length field itself. It then uses that length, which comes straight out of the file, to decide whether the optional fields are present, and reads rule->wmm_ptr at offset 18 of the 20-byte structure once the length claims 20 bytes or more. A rule placed in the last bytes of the file therefore makes the parser read up to 19 bytes past the end of the firmware image. The image comes from vmalloc() in kernel_read_file(), so with the rule at the end of a page the read falls into the guard page and oopses, with no memory debugging enabled. A length of at least offsetofend(max_bw) but below offsetofend(wmm_ptr) takes the other branch, so valid_rule() returns true having read nothing out of bounds, and the database is accepted. regdb_query_country() does not re-check the rule, and reads rule->start, rule->end, rule->max_bw and rule->cac_timeout off the end of the kmemdup()ed copy. A malformed regulatory.db is parsed by cfg80211's own request_firmware_nowait() at init time, and on demand from user space through NL80211_CMD_RELOAD_REGDB, which needs CAP_NET_ADMIN but no wireless hardware. Both paths require write access to the firmware search path and CONFIG_CFG80211_REQUIRE_SIGNED_REGDB=n. Bound the whole declared rule, not just its length field. The existing check on sizeof(rule->len) is still needed, since rule->len has to be shown to be inside the file before it can be read, so the new test goes after it. A rule reaching past the end of the file is now rejected, which fails the database rather than reading out of bounds. That also gives regdb_query_country() the bound it already assumes. Fixes: 230ebaa189af ("cfg80211: read wmm rules from regulatory database") Cc: stable@vger.kernel.org Signed-off-by: Zijing Yin Link: https://patch.msgid.link/20261015133159.1499728-1-yzjaurora@gmail.com Signed-off-by: Johannes Berg --- net/wireless/reg.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/wireless/reg.c b/net/wireless/reg.c index 11665e0a7efc..44226687349e 100644 --- a/net/wireless/reg.c +++ b/net/wireless/reg.c @@ -679,6 +679,9 @@ static bool valid_rule(const u8 *data, unsigned int size, u16 rule_ptr) /* mandatory fields */ if (rule->len < offsetofend(struct fwdb_rule, max_bw)) return false; + /* the rule must lie entirely within the database */ + if ((u8 *)rule + rule->len > data + size) + return false; if (rule->len >= offsetofend(struct fwdb_rule, wmm_ptr)) { u32 wmm_ptr = be16_to_cpu(rule->wmm_ptr) << 2; struct fwdb_wmm_rule *wmm;