On Thu, Mar 30, 2017 at 09:45:26AM -0700, Kees Cook wrote: > On Wed, Mar 29, 2017 at 11:44 PM, Tommi Rantala > <tommi.t.rantala@xxxxxxxxx> wrote: > > Hi, > > > > Running: > > > > $ sudo x86info -a > > > > On this HP ZBook 15 G3 laptop kills the x86info process with segfault and > > produces the following kernel BUG. > > > > $ git describe > > v4.11-rc4-40-gfe82203 > > > > It is also reproducible with the fedora kernel: 4.9.14-200.fc25.x86_64 > > > > Full dmesg output here: https://pastebin.com/raw/Kur2mpZq > > > > [ 51.418954] usercopy: kernel memory exposure attempt detected from > > ffff880000090000 (dma-kmalloc-256) (4096 bytes) > > This seems like a real exposure: the copy is attempting to read 4096 > bytes from a 256 byte object. > > > [...] > > [ 51.419063] Call Trace: > > [ 51.419066] read_mem+0x70/0x120 > > [ 51.419069] __vfs_read+0x28/0x130 > > [ 51.419072] ? security_file_permission+0x9b/0xb0 > > [ 51.419075] ? rw_verify_area+0x4e/0xb0 > > [ 51.419077] vfs_read+0x96/0x130 > > [ 51.419079] SyS_read+0x46/0xb0 > > [ 51.419082] ? SyS_lseek+0x87/0xb0 > > [ 51.419085] entry_SYSCALL_64_fastpath+0x1a/0xa9 > > I can't reproduce this myself, so I assume it's some specific /proc or > /sys file that I don't have. Are you able to get a strace of x86info > as it runs to see which file it is attempting to read here? Presumably this is /dev/mem, with read_mem in drivers/char/mem.c. I guess you may have locked that down on your system anyhow. ;) Thanks, Mark. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
