From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sudeep KarkadaNagesha Subject: Re: [PATCH] of: fix iteration bug over CPU reg properties Date: Mon, 21 Oct 2013 13:38:26 +0100 Message-ID: <52652042.4090200@arm.com> References: <1380904802-10432-1-git-send-email-grant.likely@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <1380904802-10432-1-git-send-email-grant.likely@linaro.org> Sender: linux-kernel-owner@vger.kernel.org To: Grant Likely , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" Cc: "rob.herring@calxeda.com" , Benjamin Herrenschmidt , Sudeep KarkadaNagesha List-Id: devicetree@vger.kernel.org Hi Grant, On 04/10/13 17:40, Grant Likely wrote: > The size of each hwid in a cpu nodes 'reg' property is defined by the > parents #address-cells property in the normal way. The cpu parsing code > has a bug where it will overrun the end of the property if > address-cells is greater than one. This commit fixes the problem by > adjusting the array size by the number of address cells. It also makes > sure address-cells isn't zero for that would cause an infinite loop. > > Signed-off-by: Grant Likely > Cc: Rob Herring > Cc: Benjamin Herrenschmidt > --- > > I discovered this during code inspection. I don't think it is an actual > bug seen in the wild, but the code does look wrong. I'd appreciate > someone take a look and confirm that I've read the code right. > Thanks for finding and fixing the bug. I have tested this on ARM64 with 2 cell reg value using [1]. Tested-by: Sudeep KarkadaNagesha Regards, Sudeep [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2013-October/206401.html > drivers/of/base.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/of/base.c b/drivers/of/base.c > index e4c9945..470b871 100644 > --- a/drivers/of/base.c > +++ b/drivers/of/base.c > @@ -263,11 +263,11 @@ static bool __of_find_n_match_cpu_property(struct device_node *cpun, > int ac, prop_len, tid; > u64 hwid; > > - ac = of_n_addr_cells(cpun); > + ac = of_n_addr_cells(cpun) ? : OF_ROOT_NODE_ADDR_CELLS_DEFAULT; > cell = of_get_property(cpun, prop_name, &prop_len); > if (!cell) > return false; > - prop_len /= sizeof(*cell); > + prop_len /= sizeof(*cell) * ac; > for (tid = 0; tid < prop_len; tid++) { > hwid = of_read_number(cell, ac); > if (arch_match_cpu_phys_id(cpu, hwid)) { >