From: Sam Ravnborg <[email protected]> Date: Wed, 2 Aug 2017 23:36:47 +0200
> And memset calls down to bzero, where %o0=buf, %o1=len > > %o0 = 0xc > %o1 = 0xfff000123c897a80 > %o2 = 0x0 > %o3 = 0xc > > So from this we know that: > res = 0xfff000123c897a80 > to + (n - 0xfff000123c897a80)) = 0xc > > The value "fff000123c897a80" really looks like a constructed address > from somewhere in the strace code, and where this constructed address > is used to provoke some unusual behaviour. > The "fff0" part may be a sparc thing. > > So far the analysis seems to match the intial conclusion that > we in this special case try to zero out the remaining memory > based on the return value of raw_copy_from_user. > And therefore we use the return value (res) which triggers the oops. Yes, the return value is bogus. > So rather than manipulating with the assembler code as suggested > in the previous mail this simpler patch could be tested: ... > - memset(to + (n - res), 0, res); > + void: /*memset(to + (n - res), 0, res);*/ Need a semicolon rather than a colon there :-)
