Commit-ID: c7a3a88c938fbe3d70c2278e082b80eb830d1c58 Gitweb: http://git.kernel.org/tip/c7a3a88c938fbe3d70c2278e082b80eb830d1c58 Author: Oleg Nesterov <o...@redhat.com> AuthorDate: Sun, 19 Aug 2012 19:10:42 +0200 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 21 Aug 2012 11:48:12 +0200
uprobes: Fix mmap_region()'s mm->mm_rb corruption if uprobe_mmap() fails This patch fixes: 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 but this is how William noticed this bug. 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. And, if nothing else, both mmap_region() and dup_mmap() return success if uprobe_mmap() fails. Change them to ignore the error code from uprobe_mmap(). Reported-and-tested-by: William Cohen <wco...@redhat.com> Signed-off-by: Oleg Nesterov <o...@redhat.com> Acked-by: Srikar Dronamraju <sri...@linux.vnet.ibm.com> Cc: <sta...@vger.kernel.org> # v3.5 Cc: Anton Arapov <an...@redhat.com> Cc: William Cohen <wco...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Link: http://lkml.kernel.org/r/20120819171042.gb26...@redhat.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- 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 3bd2280..2c8857e 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -455,8 +455,8 @@ 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 e3e8691..52e08fc 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1356,9 +1356,8 @@ 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; -- 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/
