Messages in this thread | | | Subject | Re: [PATCH 5/8] scsi: lpfc: change snprintf to scnprintf for possible overflow | From | James Smart <> | Date | Wed, 20 Mar 2019 13:27:02 -0700 |
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On 3/20/2019 10:39 AM, Greg KH wrote: > On Tue, Jan 15, 2019 at 02:41:17PM -0800, James Smart wrote: >> On 1/14/2019 5:15 PM, Kees Cook wrote: >>> On Sat, Jan 12, 2019 at 7:29 AM Willy Tarreau<w@1wt.eu> wrote: >>>> From: Silvio Cesare<silvio.cesare@gmail.com> >>>> >>>> Change snprintf to scnprintf. There are generally two cases where using >>>> snprintf causes problems. >>>> >>>> 1) Uses of size += snprintf(buf, SIZE - size, fmt, ...) >>>> In this case, if snprintf would have written more characters than what the >>>> buffer size (SIZE) is, then size will end up larger than SIZE. In later >>>> uses of snprintf, SIZE - size will result in a negative number, leading >>>> to problems. Note that size might already be too large by using >>>> size = snprintf before the code reaches a case of size += snprintf. >>>> >>>> 2) If size is ultimately used as a length parameter for a copy back to user >>>> space, then it will potentially allow for a buffer overflow and information >>>> disclosure when size is greater than SIZE. When the size is used to index >>>> the buffer directly, we can have memory corruption. This also means when >>>> size = snprintf... is used, it may also cause problems since size may become >>>> large. Copying to userspace is mitigated by the HARDENED_USERCOPY kernel >>>> configuration. >>>> >>>> The solution to these issues is to use scnprintf which returns the number of >>>> characters actually written to the buffer, so the size variable will never >>>> exceed SIZE. >>>> >>>> Signed-off-by: Silvio Cesare<silvio.cesare@gmail.com> >>>> Cc: James Smart<james.smart@broadcom.com> >>>> Cc: Dick Kennedy<dick.kennedy@broadcom.com> >>>> Cc: Dan Carpenter<dan.carpenter@oracle.com> >>>> Cc: Kees Cook<keescook@chromium.org> >>>> Cc: Will Deacon<will.deacon@arm.com> >>>> Cc: Greg KH<greg@kroah.com> >>>> Signed-off-by: Willy Tarreau<w@1wt.eu> >>> I think this needs Cc: stable. >>> >>> Reviewed-by: Kees Cook<keescook@chromium.org> >>> >>> -Kees >>> >> >> Reviewed-by: James Smart <james.smart@broadcom.com> > What ever happened to this patch? Did it get dropped somehow? > > thanks, > > greg k-h
I assume it wasn't pulled in by the scsi maintainers. I'll go ping them.
-- james
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