On 02/22/2016 10:51 AM, Gary Benson wrote:
Luis Machado wrote:
On 02/22/2016 07:40 AM, Gary Benson wrote:
Luis Machado wrote:
On 02/19/2016 09:21 AM, Gary Benson wrote:
This is an updated version of the patch I posted yesterday.
It fails silently rather than throwing if the executable is
not in the sysroot, which both fixes the sysroot-escape issue
and results in a better GDB session for the user.
Built and regtested on RHEL 6.6 x86_64.
Luis, I think this patch will fix your connection drop without
any further changes. Could you test it please?
Unfortunately it doesn't completely solve the problem i saw, as
exec_file_find will still potentially throw errors and will
disrupt the connection attempt or stop execution of a custom
sequence of commands (as Pedro noted) when "attach" is part of
the sequence.
define foo
attach <pid>
execution stops here if an error is thrown
info threads
info registers
end
It still looks like a TRY/CATCH block is needed around at least
exec_file_find.
What is throwing in exec_file_find? I'm just seeing lots of calls
to gdb_open_cloexec and openp, and I don't think either of those
should throw except for assertion failures or running out of
memory.
Not sure why i had exec_file_find in my mind. I meant to say
exec_file_attach still throws errors, when openp fails and
scratch_chan < 0. Sorry.
You shouldn't get that now, the "if (full_exec_path == NULL) return"
should have caught it. Are you still seeing thrown errors with your
setup?
Yes. With your patch applied, i still see a case where we error out.
Suppose we have a test binary gdb/test, then:
- chmod -r gdb/test
- Fire up gdbserver with a test binary: ./gdb/gdbserver/gdbserver :2345
gdb/test
- Fire up GDB: ./gdb/gdb -ex "set sysroot" -ex "tar rem :2345"
You will see something similar to the following:
Sending packet: $qXfer:exec-file:read:3486:0,fff#5f...Packet received:
l/proc/13446/exe
/proc/13446/exe: Permission denied.
(gdb) i r
The program has no registers now.
(gdb)
This was the testcase suggested by Pedro and it proved to be a good one.
There is a symbol_file_add_main call right after calling
exec_file_attach in exec_file_locate_attach, but i didn't see any
errors being thrown from that one.
You could probably race it (e.g. by deleting the file between the
calls) but generally symbol_file_add_main won't fail because
exec_file_attach would have failed if the file was missing or
inaccessible.
My idea was to guard both exec_file_attach and symbol_file_add_main. We
can't have anything in that function throwing an error that won't be
caught, otherwise the above connection attempt will fail.
Luis