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| author | Krzysztof Wilczyński <kw@linux.com> | 2021-07-29 23:37:54 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-22 11:43:04 +0200 |
| commit | 69d00a7db31d95984dabafd4951cb74d31be4491 (patch) | |
| tree | 41d949aadabbbc474c4eb0e2b18aeaef23461ec4 /drivers/pci | |
| parent | 6fb6e7b3dcec930512c89f51d4ae3185b8b92371 (diff) | |
| download | linux-rt-69d00a7db31d95984dabafd4951cb74d31be4491.tar.gz | |
PCI: Return ~0 data on pciconfig_read() CAP_SYS_ADMIN failure
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>
Diffstat (limited to 'drivers/pci')
| -rw-r--r-- | drivers/pci/syscall.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c index 7958250856d3..f602176eb8b0 100644 --- a/drivers/pci/syscall.c +++ b/drivers/pci/syscall.c @@ -23,8 +23,10 @@ SYSCALL_DEFINE5(pciconfig_read, unsigned long, bus, unsigned long, dfn, long err; int cfg_ret; + err = -EPERM; + dev = NULL; if (!capable(CAP_SYS_ADMIN)) - return -EPERM; + goto error; err = -ENODEV; dev = pci_get_bus_and_slot(bus, dfn); |