From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9D8D143E4BA; Tue, 16 Jun 2026 16:18:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781626708; cv=none; b=scZuIaK0p3KblFZOSe5TOznc5QqiXnMr9UxGxj/NJ27rK/aUgfi/U3C83vHD5PIp78ftYDw1iGfyDhn91uV69uQibqerVL/gThpx+rM3p1thTvdh5JgedUF+z/WEn8VEr1pnGcmX4ALWeTXqMRBQUbL7frAjW1VCw8cvuoXKxgM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781626708; c=relaxed/simple; bh=us9fHQU+GF3mA+I74jrf2MAqmxwiz1cZJ0wkikHha90=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=LDqnzkTSCKEntDEa54V3yCewLNBxlnji9lPyYN5i94BDfh9MAGh1rGFTmu/TfFtocsD1VhY9hnq+0meqmJ823TFTMPEKRldTOPqO/ALfjsBNbK8UfC5oWWcPYoLyutwpZmjRdDVdqEXcsyq22yX6/Y0p4W3KE3aCYh5AHpN9/+0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=nZ121xQL; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="nZ121xQL" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 507751F000E9; Tue, 16 Jun 2026 16:18:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781626707; bh=/IyJCQPTzg37ImvN5/DbNduoTmPyw6RZl7PPlAv9ql8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nZ121xQLImO+hyW94aIjuXy+y9+XsCW03Wut/h5u502pGws5/YnbG93tJmKtGfgvf wcqM7Ji+Y+bS2n7ctAa85DKkr/7eNkMI6uT7R16tIPQtw5rXADm8mALn+YXxq+G90L XVnuT5yc3DPNDmMZtrtan++aQcnqBetU3chY4qto= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yiming Qian , Keenan Dong , Han Guidong <2045gemini@gmail.com>, Zhang Cen , Davide Caratti , =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , Victor Nogueira , Jamal Hadi Salim , Rajat Gupta , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.12 053/261] net/sched: fix pedit partial COW leading to page cache corruption Date: Tue, 16 Jun 2026 20:28:11 +0530 Message-ID: <20260616145047.599588204@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145044.869532709@linuxfoundation.org> References: <20260616145044.869532709@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Rajat Gupta [ Upstream commit 899ee91156e57784090c5565e4f31bd7dbffbc5a ] tcf_pedit_act() computes the COW range for skb_ensure_writable() once before the key loop using tcfp_off_max_hint, but the hint does not account for the runtime header offset added by typed keys. This can leave part of the write region un-COW'd. Fix by moving skb_ensure_writable() inside the per-key loop where the actual write offset is known, and add overflow checking on the offset arithmetic. For negative offsets (e.g. Ethernet header edits at ingress), use skb_cow() to COW the headroom instead. Guard offset_valid() against INT_MIN, where negation is undefined. Fixes: 8b796475fd78 ("net/sched: act_pedit: really ensure the skb is writable") Reported-by: Yiming Qian Reported-by: Keenan Dong Reported-by: Han Guidong <2045gemini@gmail.com> Reported-by: Zhang Cen Reviewed-by: Han Guidong <2045gemini@gmail.com> Tested-by: Han Guidong <2045gemini@gmail.com> Reviewed-by: Davide Caratti Tested-by: Davide Caratti Reviewed-by: Toke Høiland-Jørgensen Tested-by: Toke Høiland-Jørgensen Reviewed-by: Victor Nogueira Tested-by: Victor Nogueira Acked-by: Jamal Hadi Salim Signed-off-by: Rajat Gupta Link: https://patch.msgid.link/20260531123221.48732-1-jhs@mojatatu.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- include/net/tc_act/tc_pedit.h | 1 - net/sched/act_pedit.c | 77 +++++++++++++++++++---------------- 2 files changed, 41 insertions(+), 37 deletions(-) diff --git a/include/net/tc_act/tc_pedit.h b/include/net/tc_act/tc_pedit.h index f58ee15cd858cf..cb7b82f2cbc7fd 100644 --- a/include/net/tc_act/tc_pedit.h +++ b/include/net/tc_act/tc_pedit.h @@ -15,7 +15,6 @@ struct tcf_pedit_parms { struct tc_pedit_key *tcfp_keys; struct tcf_pedit_key_ex *tcfp_keys_ex; int action; - u32 tcfp_off_max_hint; unsigned char tcfp_nkeys; unsigned char tcfp_flags; struct rcu_head rcu; diff --git a/net/sched/act_pedit.c b/net/sched/act_pedit.c index 4b65901397a888..c0a5f5d78dacd9 100644 --- a/net/sched/act_pedit.c +++ b/net/sched/act_pedit.c @@ -16,6 +16,8 @@ #include #include #include +#include +#include #include #include #include @@ -242,7 +244,6 @@ static int tcf_pedit_init(struct net *net, struct nlattr *nla, goto out_free_ex; } - nparms->tcfp_off_max_hint = 0; nparms->tcfp_flags = parm->flags; nparms->tcfp_nkeys = parm->nkeys; @@ -268,14 +269,6 @@ static int tcf_pedit_init(struct net *net, struct nlattr *nla, BITS_PER_TYPE(int) - 1, nparms->tcfp_keys[i].shift); - /* The AT option can read a single byte, we can bound the actual - * value with uchar max. - */ - cur += (0xff & offmask) >> nparms->tcfp_keys[i].shift; - - /* Each key touches 4 bytes starting from the computed offset */ - nparms->tcfp_off_max_hint = - max(nparms->tcfp_off_max_hint, cur + 4); } p = to_pedit(*a); @@ -318,15 +311,12 @@ static void tcf_pedit_cleanup(struct tc_action *a) call_rcu(&parms->rcu, tcf_pedit_cleanup_rcu); } -static bool offset_valid(struct sk_buff *skb, int offset) +static bool offset_valid(struct sk_buff *skb, int offset, int len) { - if (offset > 0 && offset > skb->len) - return false; - - if (offset < 0 && -offset > skb_headroom(skb)) + if (offset < -(int)skb_headroom(skb)) return false; - return true; + return offset <= (int)skb->len - len; } static int pedit_l4_skb_offset(struct sk_buff *skb, int *hoffset, const int header_type) @@ -393,18 +383,10 @@ TC_INDIRECT_SCOPE int tcf_pedit_act(struct sk_buff *skb, struct tcf_pedit_key_ex *tkey_ex; struct tcf_pedit_parms *parms; struct tc_pedit_key *tkey; - u32 max_offset; int i; parms = rcu_dereference_bh(p->parms); - max_offset = (skb_transport_header_was_set(skb) ? - skb_transport_offset(skb) : - skb_network_offset(skb)) + - parms->tcfp_off_max_hint; - if (skb_ensure_writable(skb, min(skb->len, max_offset))) - goto done; - tcf_lastuse_update(&p->tcf_tm); tcf_action_update_bstats(&p->common, skb); @@ -412,10 +394,11 @@ TC_INDIRECT_SCOPE int tcf_pedit_act(struct sk_buff *skb, tkey_ex = parms->tcfp_keys_ex; for (i = parms->tcfp_nkeys; i > 0; i--, tkey++) { + int write_offset, write_len; int offset = tkey->off; int hoffset = 0; - u32 *ptr, hdata; - u32 val; + u32 cur_val, val; + u32 *ptr; int rc; if (tkey_ex) { @@ -433,13 +416,15 @@ TC_INDIRECT_SCOPE int tcf_pedit_act(struct sk_buff *skb, if (tkey->offmask) { u8 *d, _d; + int at_offset; - if (!offset_valid(skb, hoffset + tkey->at)) { + if (check_add_overflow(hoffset, (int)tkey->at, &at_offset) || + !offset_valid(skb, at_offset, sizeof(_d))) { pr_info_ratelimited("tc action pedit 'at' offset %d out of bounds\n", hoffset + tkey->at); goto bad; } - d = skb_header_pointer(skb, hoffset + tkey->at, + d = skb_header_pointer(skb, at_offset, sizeof(_d), &_d); if (!d) goto bad; @@ -451,31 +436,51 @@ TC_INDIRECT_SCOPE int tcf_pedit_act(struct sk_buff *skb, } } - if (!offset_valid(skb, hoffset + offset)) { - pr_info_ratelimited("tc action pedit offset %d out of bounds\n", hoffset + offset); + if (check_add_overflow(hoffset, offset, &write_offset)) { + pr_info_ratelimited("tc action pedit offset overflow\n"); goto bad; } - ptr = skb_header_pointer(skb, hoffset + offset, - sizeof(hdata), &hdata); - if (!ptr) + if (!offset_valid(skb, write_offset, sizeof(*ptr))) { + pr_info_ratelimited("tc action pedit offset %d out of bounds\n", + write_offset); goto bad; + } + + if (write_offset < 0) { + if (skb_cow(skb, -write_offset)) + goto bad; + if (write_offset + (int)sizeof(*ptr) > 0) { + if (skb_ensure_writable(skb, + min_t(int, skb->len, + write_offset + (int)sizeof(*ptr)))) + goto bad; + } + } else { + if (check_add_overflow(write_offset, (int)sizeof(*ptr), + &write_len)) + goto bad; + if (skb_ensure_writable(skb, min_t(int, skb->len, + write_len))) + goto bad; + } + + ptr = (u32 *)(skb->data + write_offset); + cur_val = get_unaligned(ptr); /* just do it, baby */ switch (cmd) { case TCA_PEDIT_KEY_EX_CMD_SET: val = tkey->val; break; case TCA_PEDIT_KEY_EX_CMD_ADD: - val = (*ptr + tkey->val) & ~tkey->mask; + val = (cur_val + tkey->val) & ~tkey->mask; break; default: pr_info_ratelimited("tc action pedit bad command (%d)\n", cmd); goto bad; } - *ptr = ((*ptr & tkey->mask) ^ val); - if (ptr == &hdata) - skb_store_bits(skb, hoffset + offset, ptr, 4); + put_unaligned((cur_val & tkey->mask) ^ val, ptr); } goto done; -- 2.53.0