From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- drivers/pci/syscall.c | 137 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 137 insertions(+) create mode 100644 drivers/pci/syscall.c (limited to 'drivers/pci/syscall.c') diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c new file mode 100644 index 000000000..803acbf33 --- /dev/null +++ b/drivers/pci/syscall.c @@ -0,0 +1,137 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * For architectures where we want to allow direct access to the PCI config + * stuff - it would probably be preferable on PCs too, but there people + * just do it by hand with the magic northbridge registers. + */ + +#include +#include +#include +#include +#include +#include "pci.h" + +SYSCALL_DEFINE5(pciconfig_read, unsigned long, bus, unsigned long, dfn, + unsigned long, off, unsigned long, len, void __user *, buf) +{ + struct pci_dev *dev; + u8 byte; + u16 word; + u32 dword; + int err, cfg_ret; + + err = -EPERM; + dev = NULL; + if (!capable(CAP_SYS_ADMIN)) + goto error; + + err = -ENODEV; + dev = pci_get_domain_bus_and_slot(0, bus, dfn); + if (!dev) + goto error; + + switch (len) { + case 1: + cfg_ret = pci_user_read_config_byte(dev, off, &byte); + break; + case 2: + cfg_ret = pci_user_read_config_word(dev, off, &word); + break; + case 4: + cfg_ret = pci_user_read_config_dword(dev, off, &dword); + break; + default: + err = -EINVAL; + goto error; + } + + err = -EIO; + if (cfg_ret) + goto error; + + switch (len) { + case 1: + err = put_user(byte, (u8 __user *)buf); + break; + case 2: + err = put_user(word, (u16 __user *)buf); + break; + case 4: + err = put_user(dword, (u32 __user *)buf); + break; + } + pci_dev_put(dev); + return err; + +error: + /* ??? XFree86 doesn't even check the return value. They + just look for 0xffffffff in the output, since that's what + they get instead of a machine check on x86. */ + switch (len) { + case 1: + put_user(-1, (u8 __user *)buf); + break; + case 2: + put_user(-1, (u16 __user *)buf); + break; + case 4: + put_user(-1, (u32 __user *)buf); + break; + } + pci_dev_put(dev); + return err; +} + +SYSCALL_DEFINE5(pciconfig_write, unsigned long, bus, unsigned long, dfn, + unsigned long, off, unsigned long, len, void __user *, buf) +{ + struct pci_dev *dev; + u8 byte; + u16 word; + u32 dword; + int err = 0; + + if (!capable(CAP_SYS_ADMIN) || + security_locked_down(LOCKDOWN_PCI_ACCESS)) + return -EPERM; + + dev = pci_get_domain_bus_and_slot(0, bus, dfn); + if (!dev) + return -ENODEV; + + switch (len) { + case 1: + err = get_user(byte, (u8 __user *)buf); + if (err) + break; + err = pci_user_write_config_byte(dev, off, byte); + if (err) + err = -EIO; + break; + + case 2: + err = get_user(word, (u16 __user *)buf); + if (err) + break; + err = pci_user_write_config_word(dev, off, word); + if (err) + err = -EIO; + break; + + case 4: + err = get_user(dword, (u32 __user *)buf); + if (err) + break; + err = pci_user_write_config_dword(dev, off, dword); + if (err) + err = -EIO; + break; + + default: + err = -EINVAL; + break; + } + pci_dev_put(dev); + return err; +} -- cgit v1.3.1