From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 483F43D9556 for ; Mon, 31 Aug 2026 22:59:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788217175; cv=none; b=r6cXkB+M1WxrYUz3V0bbYOtDZ8dOIjEZul9Sg79EL2mj792QHsdTrrvrIVX1mKMyzHfdle188B7E/G1UsURY5iA3rTT+uL4P+vGk/s8371t/nt6lTtLhltCYvF8zFLyRWr7cfEnruknn0GisJ8mY7KfFk5O6+lZJUbd+XhO4SK8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788217175; c=relaxed/simple; bh=9w2fJMFJfoMKZHr3yUEMJiUqkNOTUPGngPWS5P6a/8U=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=b5n9ScCDfOcKzRoeLFScM/uidS3f9cVN+XDpIkzqVuHwWVeyjeCEFDSa+NO+tjiORsz5N/azVPTg5ab/5/VkPOEsN5Hur5tvDnqvhIdQWgCn3RCbSLPWzvP/KwoCU6HkT5lZ1ffAkEMN3t5UW75yfM4C7aLSRnuy5Aebiwqxcrg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=MUj8qOnz; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=P21yFFV8; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MUj8qOnz"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="P21yFFV8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1788217169; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=uK4TTkBG9dUIPsUOqB9N1xZ2lSliw1R9iyocIf27jkE=; b=MUj8qOnzbMZkye6K1j+sGnqL49MMN0vQ2j1/peMVBC+1+gDT/jc3jLHozoe0h7cT/fzCvZ /MlBWqu9MUulTZrVUt5ajzRmEjwxu134mQJEqH22ylPOi3UDpIcZoAL1zSaiV76LhMl+sy W+UT9BuhXV6Is6ERetEp4fR8nmV6Bz4= Received: from mail-qv1-f72.google.com (mail-qv1-f72.google.com [209.85.219.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-486-803ys_6gOcCLxwkhLFzLLw-1; Mon, 31 Aug 2026 18:59:28 -0400 X-MC-Unique: 803ys_6gOcCLxwkhLFzLLw-1 X-Mimecast-MFC-AGG-ID: 803ys_6gOcCLxwkhLFzLLw_1788217167 Received: by mail-qv1-f72.google.com with SMTP id 6a1803df08f44-8f39a46efd9so6396476d6.1 for ; Mon, 31 Aug 2026 15:59:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1788217167; x=1788821967; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to :content-type; bh=uK4TTkBG9dUIPsUOqB9N1xZ2lSliw1R9iyocIf27jkE=; b=P21yFFV8QnFHo56ymdMf5WTs3MURnf4Q+SEFO29u1vxQXalh3dVLIRvxq47r0TaoGA 1d+VE0b4dGBZRj+up8I3JR3xM6AZDWB4pIItf+PIeL9JOvqvhuAc3sURPYPAWmpb4lRp dHwi88VOrS/sTbAFl+FXzT4ZfTHB4N92hkKjTjtJyRb9wI2CUTAgi2cI5XlxQcSO1zqZ c8HZNN7bNvGPRtqguClnYqc8vwB4YCyfTg2It80lPPjGxMGN6iA6503bmNoB8UsypwGB P/eo8d16fXWrrNxIUu8Id1TPjShX3BK8PsM9JiaY/5RdRX3uZ/Sn9aRtq+eUbfLoevTQ fbiw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788217167; x=1788821967; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=uK4TTkBG9dUIPsUOqB9N1xZ2lSliw1R9iyocIf27jkE=; b=kPfOlPlVseTpYUn6KPBhtwVLGLBsbAUF5O4UGKusUdGSmopkPdoESdzZlz5Vv5Kw4+ WxrXF3JHNQ0pAC80dWY8b2QU6B0Vx4v+GFgPbdpvuahNWcyISeMDTn6JgjA80j39hNdz MHJvlN9WIPUD05+p2LEPjisWg4ruZpeN3AGvgB9+u5JMoweJaFLVRpTJhQZx29FxFlsf pnS5L8uLIAG2Oscdz2ar9ElVL618+jeJMqCizsS/UC9pwZVXkUWEOc8sMqkPIasoi9Fr R4nH31yypYpa26X/jC476RHXlYATjlGZXKLcPH4YaSxG6GZDBgaF8eXifWAvM6HFlusM ycqQ== X-Gm-Message-State: AFuF++l8jDoMwFi/VN719fVMLXZOoZqXZLtjICxPoBvf2WyH4X1+D0wy oSNEVwaVK8hKJRYgbXQ8ResH7TaATd2ZGqlqS8Ml4qYzcSPvskPWPwg03pnfUKLZqVWFrxt9cwo 7yxE7s8uDWVHRm+YSV//eMcx9kYfwSk/sLPx/LqW7saCMMmy6kXViqVx7O/gILQ== X-Gm-Gg: AYBFou2AQ7pezdZpuyTmeBL1AlIBfK0eSrSjSatsxywUJOpawH5zMfv2hrLhbOL00RN p1i4Fw9rWL9nGSlIIkLTfzdpHXAZplDUuXyV1zgLvuquKi97tQsU+x/p9PWT7K2TWYRdtrGNnZh CFw2b1KiXnTSriTfl3JDHN7dbZrMw80cmQnWU87VxPsRVjkjVDgWyIF2nujRabNtc/K5tPDeYpZ vciaxVb9WAVvsgPDXTcd7mWJjobRUBTIb/0joDSIU/GIuAkuheNxk6y64NxNxs62W6+Gv1TnJv0 fNfKu/4p9X7tYCPQ3/kZsEpK7w34EzzaGUhHSuKFP1mGNMsX7VVJUZZnqY1luCLs0KFyMvaXmDU r3fbMpiAJmggFCYVLKb7hb79Ip9VvldFL1blkoxx0WybZs1EN X-Received: by 2002:a05:6214:5d87:b0:90a:7f98:15f3 with SMTP id 6a1803df08f44-90e956e7aefmr21568716d6.2.1788217167417; Mon, 31 Aug 2026 15:59:27 -0700 (PDT) X-Received: by 2002:a05:6214:5d87:b0:90a:7f98:15f3 with SMTP id 6a1803df08f44-90e956e7aefmr21568266d6.2.1788217166911; Mon, 31 Aug 2026 15:59:26 -0700 (PDT) Received: from ?IPV6:2603:6000:1d40:9300:d6cc:b253:d867:f7d1? ([2603:6000:1d40:9300:d6cc:b253:d867:f7d1]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-90ce4464bc8sm95051806d6.19.2026.08.31.15.59.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 31 Aug 2026 15:59:26 -0700 (PDT) Message-ID: Date: Mon, 31 Aug 2026 17:59:25 -0500 Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/1] nfs-utils: mount: fix snprintf return value handling in error formatting To: Olga Kornievskaia Cc: linux-nfs@vger.kernel.org References: <20260825185323.27151-1-okorniev@redhat.com> Content-Language: en-US From: Steve Dickson In-Reply-To: <20260825185323.27151-1-okorniev@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/25/26 2:53 PM, Olga Kornievskaia wrote: > snprintf() returns the number of bytes that would have been written > if sufficient space were available, not the number actually written. > When the formatted string exceeds PATH_MAX (e.g. due to a long > progname), the return value exceeds the buffer size. Using that > unclamped value as an index into errbuf produces an out-of-bounds > pointer, and subsequent snprintf() calls write past the buffer. > > Add errbuf_clamp() to bound the position to the valid range before > it is used as a buffer index. Apply it in rpc_mount_errors(), > sys_mount_errors(), and rpc_strerror(). > > Fixes: 6e54f6179cb9 ("text-based mount.nfs: Add text-based error reporting function") > Signed-off-by: Olga Kornievskaia Committed... (tag: nfs-utils-2-9-3-rc2) steved. > --- > utils/mount/error.c | 24 ++++++++++++++++++++++-- > 1 file changed, 22 insertions(+), 2 deletions(-) > > diff --git a/utils/mount/error.c b/utils/mount/error.c > index d6cbdea1..4dace8f5 100644 > --- a/utils/mount/error.c > +++ b/utils/mount/error.c > @@ -54,6 +54,21 @@ extern char *progname; > static char errbuf[PATH_MAX]; > static char *erreob = &errbuf[PATH_MAX]; > > +/* > + * Clamp a buffer position to the valid range for errbuf. > + * snprintf() returns the number of bytes that would have been written, > + * which can exceed the buffer size on truncation. Using that unclamped > + * value as an index into errbuf produces an out-of-bounds pointer. > + */ > +static int errbuf_clamp(int pos) > +{ > + if (pos < 0) > + return 0; > + if (pos >= PATH_MAX) > + return PATH_MAX - 1; > + return pos; > +} > + > /* Convert RPC errors into strings */ > static int rpc_strerror(int spos) > { > @@ -62,6 +77,8 @@ static int rpc_strerror(int spos) > char *ptr, *estr = clnt_sperrno(cf_stat); > char *tmp; > > + spos = errbuf_clamp(spos); > + > if (estr) { > if ((ptr = strchr(estr, ':'))) > estr = ++ptr; > @@ -72,9 +89,9 @@ static int rpc_strerror(int spos) > _("System Error: %s"), > strerror(cf_errno)); > else { > - if (cf_errno) > + if (cf_errno) > pos = snprintf(tmp, (erreob - tmp), > - _("RPC Error:%s; errno = %s"), > + _("RPC Error:%s; errno = %s"), > estr, strerror(cf_errno)); > else > pos = snprintf(tmp, (erreob - tmp), > @@ -109,6 +126,7 @@ void rpc_mount_errors(char *server, int will_retry, int bg) > _("%s: mount to NFS server '%s' failed: "), > progname, server); > > + pos = errbuf_clamp(pos); > tmp = &errbuf[pos]; > if (rpc_createerr.cf_stat == RPC_TIMEDOUT) { > if (will_retry) > @@ -119,6 +137,7 @@ void rpc_mount_errors(char *server, int will_retry, int bg) > _("timed out, giving up")); > } else { > pos += rpc_strerror(pos); > + pos = errbuf_clamp(pos); > tmp = &errbuf[pos]; > if (bg) { > if (will_retry) > @@ -164,6 +183,7 @@ void sys_mount_errors(char *server, int error, int will_retry, int bg) > _("%s: mount to NFS server '%s' failed: "), > progname, server); > > + pos = errbuf_clamp(pos); > tmp = &errbuf[pos]; > if (error == ETIMEDOUT) { > if (will_retry)