From: Krzysztof Wilczyński <kw@linux.com> stable inclusion from stable-5.10.67 commit 72f2be34327221ca790c27f9204ffec1329a1c12 bugzilla: 182619 https://gitee.com/openeuler/kernel/issues/I4EWO7 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- 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: Chen Jun <chenjun102@huawei.com> Acked-by: Weilong Chen <chenweilong@huawei.com> Signed-off-by: Chen Jun <chenjun102@huawei.com> --- drivers/pci/syscall.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) 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); -- 2.20.1