diff options
author | Oleg Nesterov <oleg@redhat.com> | 2014-05-19 20:40:54 +0200 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2014-06-05 12:30:07 +0200 |
commit | 41ccba029e9492dd0fc1bf5c23b72c6322a6dfe9 (patch) | |
tree | d12da7b78672c157b26a32b2d8a9067f6fe9d6e7 /kernel/events/uprobes.c | |
parent | c184c980de30dc5f6fec4b281928aa6743708da9 (diff) | |
download | linux-next-41ccba029e9492dd0fc1bf5c23b72c6322a6dfe9.tar.gz |
uprobes: Shift ->readpage check from __copy_insn() to uprobe_register()
copy_insn() fails with -EIO if ->readpage == NULL, but this error
is not propagated unless uprobe_register() path finds ->mm which
already mmaps this file. In this case (say) "perf record" does not
actually install the probe, but the user can't know about this.
Move this check into uprobe_register() so that this problem can be
detected earlier and reported to user.
Note: this is still not perfect,
- copy_insn() and arch_uprobe_analyze_insn() should be called
by uprobe_register() but this is not simple, we need vm_file
for read_mapping_page() (although perhaps we can pass NULL),
and we need ->mm for is_64bit_mm() (although this logic is
broken anyway).
- uprobe_register() should be called by create_trace_uprobe(),
not by probe_event_enable(), so that an error can be detected
at "perf probe -x" time. This also needs more changes in the
core uprobe code, uprobe register/unregister interface was
poorly designed from the very beginning.
Reported-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140519184054.GA6750@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/events/uprobes.c')
-rw-r--r-- | kernel/events/uprobes.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 3b02c72938a8..c56b13e3b5e1 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -536,9 +536,6 @@ static int __copy_insn(struct address_space *mapping, struct file *filp, void *insn, int nbytes, loff_t offset) { struct page *page; - - if (!mapping->a_ops->readpage) - return -EIO; /* * Ensure that the page that has the original instruction is * populated and in page-cache. @@ -879,6 +876,9 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer * if (!uc->handler && !uc->ret_handler) return -EINVAL; + /* copy_insn()->read_mapping_page() needs ->readpage() */ + if (!inode->i_mapping->a_ops->readpage) + return -EIO; /* Racy, just to catch the obvious mistakes */ if (offset > i_size_read(inode)) return -EINVAL; |