BugLink: https://bugs.launchpad.net/bugs/1946802
commit
a8bd29bd49c4156ea0ec5a97812333e2aeef44e7 upstream.
The pciconfig_read() syscall reads PCI configuration space using
hardware-dependent config accessors.
If the read fails on PCI, most accessors don't return an error; they
pretend the read was successful and got ~0 data from the device, so the
syscall returns success with ~0 data in the buffer.
When the accessor does return an error, pciconfig_read() normally fills the
user's buffer with ~0 and returns an error in errno. But after
e4585da22ad0 ("pci syscall.c: Switch to refcounting API"), we don't fill
the buffer with ~0 for the EPERM "user lacks CAP_SYS_ADMIN" error.
Userspace may rely on the ~0 data to detect errors, but after
e4585da22ad0,
that would not detect CAP_SYS_ADMIN errors.
Restore the original behaviour of filling the buffer with ~0 when the
CAP_SYS_ADMIN check fails.
[bhelgaas: commit log, fold in Nathan's fix
https://lore.kernel.org/r/
20210803200836.500658-1-nathan@kernel.org]
Fixes: e4585da22ad0 ("pci syscall.c: Switch to refcounting API")
Link: https://lore.kernel.org/r/20210729233755.1509616-1-kw@linux.com
Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>
long err;
int cfg_ret;
+ err = -EPERM;
+ dev = NULL;
if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
+ goto error;
err = -ENODEV;
dev = pci_get_domain_bus_and_slot(0, bus, dfn);