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| author | Krzysztof Wilczyński <kw@linux.com> | 2021-07-30 02:37:54 +0300 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2021-08-04 00:55:11 +0300 |
| commit | a8bd29bd49c4156ea0ec5a97812333e2aeef44e7 (patch) | |
| tree | 51d0dc42118ca98a06cfcf3dc307fa04fb937c51 /drivers/pci/syscall.c | |
| parent | b12d93e9958e028856cbcb061b6e64728ca07755 (diff) | |
| download | linux-a8bd29bd49c4156ea0ec5a97812333e2aeef44e7.tar.xz | |
PCI: Return ~0 data on pciconfig_read() CAP_SYS_ADMIN failure
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
Diffstat (limited to 'drivers/pci/syscall.c')
| -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 8b003c890b87..c9f03418e71e 100644 --- a/drivers/pci/syscall.c +++ b/drivers/pci/syscall.c @@ -22,8 +22,10 @@ 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_domain_bus_and_slot(0, bus, dfn); |