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From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: coverity-bot <keescook@chromium.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
	Alexey Romanov <avromanov@sberdevices.ru>,
	linux-kernel@vger.kernel.org, Nick Terrell <terrelln@fb.com>,
	Minchan Kim <minchan@kernel.org>,
	Suleiman Souhlal <suleiman@google.com>,
	Nitin Gupta <ngupta@vflare.org>, Jens Axboe <axboe@kernel.dk>,
	Nhat Pham <nphamcs@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-block@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
	linux-next@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: Coverity: zram_recompress(): OVERRUN
Date: Fri, 11 Nov 2022 09:37:10 +0900	[thread overview]
Message-ID: <Y22ZNtdH9s+cuL9l@google.com> (raw)
In-Reply-To: <202211100847.388C61B3@keescook>

On (22/11/10 08:47), coverity-bot wrote:
[..]
> 1704     	class_index_old = zs_lookup_class_index(zram->mem_pool, comp_len_old);
> 1705     	/*
> 1706     	 * Iterate the secondary comp algorithms list (in order of priority)
> 1707     	 * and try to recompress the page.
> 1708     	 */
> 1709     	for (; prio < prio_max; prio++) {
> vvv     CID 1527270:    (OVERRUN)
> vvv     Overrunning array "zram->comps" of 4 8-byte elements at element index 4 (byte offset 39) using index "prio" (which evaluates to 4).
> 1710     		if (!zram->comps[prio])
> 1711     			continue;
> 1712
> 1713     		/*
> 1714     		 * Skip if the object is already re-compressed with a higher
> 1715     		 * priority algorithm (or same algorithm).

prio_max is always limited and max value it can have is 4 (ZRAM_MAX_COMPS).
Depending on use case we can limit prio_max even to lower values.

So we have

	for (; prio < 4; prio++) {
		foo = comps[prio];
	}

I don't see how prio can be 4 inside of this loop.

  parent reply	other threads:[~2022-11-11  0:37 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-10 16:47 Coverity: zram_recompress(): OVERRUN coverity-bot
2022-11-11  0:26 ` Sergey Senozhatsky
2022-11-11  3:15   ` Kees Cook
2022-11-11 10:39     ` Sergey Senozhatsky
2022-11-11  0:37 ` Sergey Senozhatsky [this message]
2022-11-11  0:42   ` Sergey Senozhatsky
2022-11-11  3:16     ` Kees Cook

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