From 7dcf371a35632f035baf77bcf2c129165f772ce4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?=C3=96mer=20Mete=20Kaya?= Date: Tue, 8 Sep 2026 19:18:01 +0300 Subject: [PATCH] nfc: llcp: fix slab-out-of-bounds reads when logging service names MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit nfc_llcp_wks_sap() and nfc_llcp_build_sdreq_tlv() pass non-null- terminated strings to pr_debug() using the %s format specifier. The buffers are allocated via kmemdup() or come from netlink attributes and are not guaranteed to be null-terminated, causing __dynamic_pr_debug() to read beyond the allocated region: KASAN: slab-out-of-bounds Read in __dynamic_pr_debug Fix both call sites by using %.*s with the explicit length to limit the output to the actual length of the string. Fixes: d9b8d8e19b07 ("NFC: llcp: Service Name Lookup netlink interface") Reported-by: syzbot+1e3df0852e82c21ca418@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1e3df0852e82c21ca418 Signed-off-by: Ömer Mete Kaya Link: https://patch.msgid.link/20260908161952.731468-1-omermetekaya0@gmail.com Signed-off-by: David Heidelberg --- net/nfc/llcp_commands.c | 2 +- net/nfc/llcp_core.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/net/nfc/llcp_commands.c b/net/nfc/llcp_commands.c index ca89fe967d6a..80a00938c869 100644 --- a/net/nfc/llcp_commands.c +++ b/net/nfc/llcp_commands.c @@ -135,7 +135,7 @@ struct nfc_llcp_sdp_tlv *nfc_llcp_build_sdreq_tlv(u8 tid, const char *uri, { struct nfc_llcp_sdp_tlv *sdreq; - pr_debug("uri: %s, len: %zu\n", uri, uri_len); + pr_debug("uri: %.*s, len: %zu\n", (int)uri_len, uri, uri_len); /* sdreq->tlv_len is u8, takes uri_len, + 3 for header, + 1 for NULL */ if (WARN_ON_ONCE(uri_len > U8_MAX - 4)) diff --git a/net/nfc/llcp_core.c b/net/nfc/llcp_core.c index def712e1b2b2..74bf817007cf 100644 --- a/net/nfc/llcp_core.c +++ b/net/nfc/llcp_core.c @@ -358,7 +358,7 @@ static int nfc_llcp_wks_sap(const char *service_name, size_t service_name_len) { int sap, num_wks; - pr_debug("%s\n", service_name); + pr_debug("%.*s\n", (int)service_name_len, service_name); if (service_name == NULL) return -EINVAL;