On Thu, Feb 2, 2017 at 11:36 PM, Jacob Champion <[email protected]> wrote: > On 02/02/2017 02:32 PM, Yann Ylavic wrote: >> >> On Thu, Feb 2, 2017 at 11:19 PM, Jacob Champion <[email protected]> >> wrote: >>> >>> Idle thoughts: "Cannot access memory" in this case could be a red >>> herring, >>> if Niklas' gdb can't peer into mmap'd memory spaces [1]. It seems >>> reasonable >>> that the data in question could be mmap'd, given the nice round address >>> and >>> 4 MiB length (equal to APR_MMAP_LIMIT). >>> >>> That doesn't mean we're looking in the wrong place, though, since SIGBUS >>> can >>> also be generated by an out-of-bounds access to an mmap'd region. >> >> >> Right, looks like the memory has been unmapped though (SIGBUS) before >> being (re)used. > > Oh, I thought an access after an unmap would SIGSEGV instead of SIGBUS. I > haven't ever tested that out; I should try it...
Hmm, Linux raises SIGBUS if an mmap is used after the underlying file has been truncated (see [1]). Couldn't htcacheclean or alike do something like this? "EnableMMAP off" could definitely help here. [1] http://man7.org/linux/man-pages/man2/mmap.2.html
