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 B37E227874F for ; Mon, 20 Jul 2026 15:19:32 +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=1784560773; cv=none; b=KXIIQ3NDUTSMwaE8KtY/kPoo90k6wvllTtPCinW8FKXlh/wI91H5Wj5aSlFx5695XqzN8fv6EKDONGC5cLORAsnPZiuDcLtx1C3SEFQ4qUhtHi/Z+A4sYSv2Fv5miariBt3w7jbcPIhKnfyEUMRAQZvFDeDDCNH5vZ5pUCYsf9o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784560773; c=relaxed/simple; bh=hN26Qab+nDTmWW8xJS8DO6OsWm2ciC5mIIzcfN6PytY=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=Lxkxzsm3lHQxo1yH212FmfcGaHpAR6V1QUuY03VgDiV7endCT7+u403LPvxSuTiUBWpUEIzgHk/kgWM3k8ly9GpmCyVn707WCmXazsI3WUTlF1P/qEFkZzctHz//Rh6t/ktAs4njEi809H/BusSDI7ONJYHmQK5F/902EtxUWRs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=C1ysplEq; 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="C1ysplEq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 258391F000E9; Mon, 20 Jul 2026 15:19:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784560772; bh=umPZCrubznqdAZTvFhwyNp+NIkOYF+8H9WULwaJCTPA=; h=Subject:To:Cc:From:Date; b=C1ysplEq421d/DUzG1xYjV7X0cKgg2p4iD8GSUg68MmWmeQvqwtns/9hnRDPqmMu6 77x3+kfwU84obAq+6P1NwY5Iax8RGRHX00GTOmB15Ov3goBvBkAVYu1k5uB3Goes8w cXVDyOoOUo0RrMKWZWh1U/ay72I1iRrZJMK8mj2s= Subject: FAILED: patch "[PATCH] dm-verity: fix buffer overflow in FEC calculation" failed to apply to 5.15-stable tree To: mpatocka@redhat.com,samitolvanen@google.com Cc: From: Date: Mon, 20 Jul 2026 17:19:06 +0200 Message-ID: <2026072006-geometry-exhale-420b@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 31d6e6c0ba8d5a7bd59660035a089307100c5e8e # git commit -s git send-email --to '' --in-reply-to '2026072006-geometry-exhale-420b@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 31d6e6c0ba8d5a7bd59660035a089307100c5e8e Mon Sep 17 00:00:00 2001 From: Mikulas Patocka Date: Wed, 1 Jul 2026 18:13:50 +0200 Subject: [PATCH] dm-verity: fix buffer overflow in FEC calculation MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There's a buffer overflow in dm-verity-fec: if (neras && *neras <= v->fec->roots) fio->erasures[(*neras)++] = i; This allows *neras to reach roots + 1 (the post-increment pushes it past roots). This value is then passed as no_eras to decode_rs8(). Inside the RS decoder (lib/reed_solomon/decode_rs.c:113-121), the erasure locator polynomial loop writes lambda[j] where j can reach nroots + 1 — one element past the end of lambda[] (which is sized nroots + 1, valid indices 0..nroots). The out-of-bounds write lands on syn[0], corrupting the syndrome buffer. Signed-off-by: Mikulas Patocka Assisted-by: Claude:claude-opus-4-6 Cc: stable@vger.kernel.org Fixes: a739ff3f543a ("dm verity: add support for forward error correction") Reviewed-by: Sami Tolvanen Signed-off-by: Mikulas Patocka diff --git a/drivers/md/dm-verity-fec.c b/drivers/md/dm-verity-fec.c index 85ad9dc210ff..c79f60df3a90 100644 --- a/drivers/md/dm-verity-fec.c +++ b/drivers/md/dm-verity-fec.c @@ -220,7 +220,7 @@ static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io, PTR_ERR(bbuf)); /* assume the block is corrupted */ - if (neras && *neras <= v->fec->roots) + if (neras && *neras < v->fec->roots) fio->erasures[(*neras)++] = i; continue; @@ -238,7 +238,7 @@ static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io, * skip if we have already found the theoretical * maximum number (i.e. fec->roots) of erasures */ - if (neras && *neras <= v->fec->roots && + if (neras && *neras < v->fec->roots && fec_is_erasure(v, io, want_digest, bbuf)) fio->erasures[(*neras)++] = i; } diff --git a/drivers/md/dm-verity-fec.h b/drivers/md/dm-verity-fec.h index 50b5e187d5cc..3885b514fc23 100644 --- a/drivers/md/dm-verity-fec.h +++ b/drivers/md/dm-verity-fec.h @@ -47,7 +47,7 @@ struct dm_verity_fec { /* per-bio data */ struct dm_verity_fec_io { struct rs_control *rs; /* Reed-Solomon state */ - int erasures[DM_VERITY_FEC_MAX_ROOTS + 1]; /* erasures for decode_rs8 */ + int erasures[DM_VERITY_FEC_MAX_ROOTS]; /* erasures for decode_rs8 */ u8 *output; /* buffer for corrected output */ unsigned int level; /* recursion level */ unsigned int nbufs; /* number of buffers allocated */