Messages in this thread Patch in this message | | | Date | Mon, 27 Apr 2015 18:17:15 +0300 | From | "Ivan.khoronzhuk" <> | Subject | Re: [PATCH] firmware: dmi_scan: Trim DMI table length before exporting it |
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Hi, Jean
On 26.04.15 23:47, Jean Delvare wrote: > The SMBIOS v3 entry points specify a maximum length for the DMI table, > not the exact length. Thus there may be garbage after the end-of-table > marker, which we don't want to export to user-space. Adjust dmi_len > when we find the end-of-table marker, so that only the actual table > payload is exported.
According to above it seems that change doesn't affect SMBIOS < 3.
> > Signed-off-by: Jean Delvare <jdelvare@suse.de> > Cc: Ivan Khoronzhuk <ivan.khoronzhuk@globallogic.com> > --- > drivers/firmware/dmi_scan.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > --- linux-4.1-rc0.orig/drivers/firmware/dmi_scan.c 2015-04-26 18:56:15.657111185 +0200 > +++ linux-4.1-rc0/drivers/firmware/dmi_scan.c 2015-04-26 22:42:59.183547584 +0200 > @@ -108,15 +108,19 @@ static void dmi_decode_table(u8 *buf, > if (data - buf < dmi_len - 1) > decode(dm, private_data); > > + data += 2; > + i++; > + > /* > * 7.45 End-of-Table (Type 127) [SMBIOS reference spec v3.0.0] > */ > if (dm->type == DMI_ENTRY_END_OF_TABLE) > break; > - > - data += 2; > - i++; > } > + > + /* Trim DMI table length if needed */ > + if (dmi_len > data - buf) > + dmi_len = data - buf;
Why is it checked here? Wouldn't be better to simply assign: dmi_len = data - buf; I guess it's supposed to not trim table in case of exit by i<dmi_num or even !dmi_num. But in this case, probably, it be better to do it in the cycle:
if (dmi->type == DMI_ENTRY_END_OF_TABLE) { dmi_len = data - buf; break; }
just to avoid redundant check.
But question is, what if we exit by i<dmi_num? Wouldn't be better to trim buffer in such case also?
> } > > static phys_addr_t dmi_base; > @@ -125,8 +129,9 @@ static int __init dmi_walk_early(void (* > void *)) > { > u8 *buf; > + u32 orig_dmi_len = dmi_len; > > - buf = dmi_early_remap(dmi_base, dmi_len); > + buf = dmi_early_remap(dmi_base, orig_dmi_len); > if (buf == NULL) > return -1; > > @@ -134,7 +139,7 @@ static int __init dmi_walk_early(void (* > > add_device_randomness(buf, dmi_len); > > - dmi_early_unmap(buf, dmi_len); > + dmi_early_unmap(buf, orig_dmi_len); > return 0; > } > >
-- Regards, Ivan Khoronzhuk
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