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authorKrzysztof Wilczyński <kw@linux.com>2021-07-30 02:37:54 +0300
committerBjorn Helgaas <bhelgaas@google.com>2021-08-04 00:55:11 +0300
commita8bd29bd49c4156ea0ec5a97812333e2aeef44e7 (patch)
tree51d0dc42118ca98a06cfcf3dc307fa04fb937c51 /drivers/pci/syscall.c
parentb12d93e9958e028856cbcb061b6e64728ca07755 (diff)
downloadlinux-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.c4
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);