Re: [patch 077/232] sdio: fix read buffer overflow

David Vrabel
2009-10-01T11:13:40Z

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Jonathan Cameron wrote:
> Hi All,
>
> This patch is causing a regression with libertas 8686.
> It's only finding 3 strings which I'm guessing means
> it is an invalid CISTPL_VERS_1. Unfortunately the libertas_sdio
> code relies on a string in one of them to tell it what model of
> card we have.
>
> Can someone confirm what the CIS_VERS_1 spec actually is?
> I've found one vague reference to entries 3 and 4 being optional
> but the simplified sdio spec refers to the pcmcia 3.2.10 spec
> which I don't have easy access to.

It's harmless if the tuple contains fewer so I think we should just try
and parse as many strings as possible. Does this patch fix your regression?

David
--
David Vrabel, Senior Software Engineer, Drivers
CSR, Churchill House, Cambridge Business Park, Tel: +44 (0)1223 692562
Cowley Road, Cambridge, CB4 0WZ http://www.csr.com/

Member of the CSR plc group of companies. CSR plc registered in England and Wales, registered number 4187346, registered office Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, United Kingdom

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>From 6ab16f09790e98832ee0077d67f8663bcf2b0ad1 Mon Sep 17 00:00:00 2001
From: David Vrabel <david.vrabel@csr.com>
Date: Thu, 1 Oct 2009 11:56:25 +0100
Subject: [PATCH] mmc: sdio: don't require CISTPL_VERS_1 to contain 4 strings

The PC Card 8.0 specification (vol. 4, section 3.2.10) says the
TPLLV1_INFO field of the CISTPL_VERS_1 tuple must contain 4 strings.
Some cards don't have all 4 so just parse as many as we can.

Signed-off-by: David Vrabel <david.vrabel@csr.com>
---
drivers/mmc/core/sdio_cis.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/core/sdio_cis.c b/drivers/mmc/core/sdio_cis.c
index 6636354..b2dc4a7 100644
--- a/drivers/mmc/core/sdio_cis.c
+++ b/drivers/mmc/core/sdio_cis.c
@@ -29,6 +29,8 @@ static int cistpl_vers_1(struct mmc_card *card, struct sdio_func *func,
unsigned i, nr_strings;
char **buffer, *string;

+ /* Find all null-terminated (including zero length) strings in
+ the TPLLVL1_INFO field. Trailing garbage is ignored. */
buf += 2;
size -= 2;

@@ -39,9 +41,7 @@ static int cistpl_vers_1(struct mmc_card *card, struct sdio_func *func,
if (buf[i] == 0)
nr_strings++;
}
-
- if (nr_strings < 4) {
- printk(KERN_WARNING "SDIO: ignoring broken CISTPL_VERS_1\n");
+ if (nr_strings == 0) {
return 0;
}

--
1.6.3.3