* Oleg Nesterov <o...@redhat.com> [2012-07-28 18:31:57]: > https://bugzilla.redhat.com/show_bug.cgi?id=843640 > > If mmap_region()->uprobe_mmap() fails, unmap_and_free_vma path > does unmap_region() but does not remove the soon-to-be-freed vma > from rb tree (actually there are more problems). > > Perhaps we could do do_munmap() + return in this case, but in fact > it is simply wrong to abort if uprobe_mmap() fails. Until at least > we move the !UPROBE_COPY_INSN code from install_breakpoint() to > uprobe_register(). > > For example, uprobe_mmap()->install_breakpoint() can fail if the > probed insn is not supported (remember, uprobe_register() succeeds > if nobody mmaps inode/offset), mmap() should not fail in this case. > > dup_mmap()->uprobe_mmap() is wrong too by the same reason, fork() > can race with uprobe_register() and fail for no reason if it wins > the race and does install_breakpoint() first. > > Change mmap_region() and dup_mmap() to ignore the error code from > uprobe_mmap(). > > Reported-by: William Cohen <wco...@redhat.com> > Signed-off-by: Oleg Nesterov <o...@redhat.com> > Cc: <sta...@vger.kernel.org> # v3.5
After discussions with Oleg, its very clear that this apt fix for now. Acked-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com> > --- > kernel/fork.c | 4 ++-- > mm/mmap.c | 5 ++--- > 2 files changed, 4 insertions(+), 5 deletions(-) > > diff --git a/kernel/fork.c b/kernel/fork.c > index ab5211b..54bb88a 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -454,8 +454,8 @@ static int dup_mmap(struct mm_struct *mm, struct > mm_struct *oldmm) > if (retval) > goto out; > > - if (file && uprobe_mmap(tmp)) > - goto out; > + if (file) > + uprobe_mmap(tmp); > } > /* a new mm has just been created */ > arch_dup_mmap(oldmm, mm); > diff --git a/mm/mmap.c b/mm/mmap.c > index 4fe2697..f25fd3f 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -1355,9 +1355,8 @@ out: > } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) > make_pages_present(addr, addr + len); > > - if (file && uprobe_mmap(vma)) > - /* matching probes but cannot insert */ > - goto unmap_and_free_vma; > + if (file) > + uprobe_mmap(vma); > > return addr; > > -- > 1.5.5.1 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
