From 488debb9971bc7d0edd6d8080ba78ca02a04f6c4 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Thu, 5 Jan 2017 17:15:01 +0000 Subject: drivers: char: mem: Fix thinkos in kmem address checks When borrowing the pfn_valid() check from mmap_kmem(), somebody managed to get physical and virtual addresses spectacularly muddled up, such that we've ended up with checks for one being the other. Whilst this does indeed prevent out-of-bounds accesses crashing, on most systems it also prevents the more desirable use-case of working at all ever. Check the *virtual* offset correctly for what it is. Furthermore, do so in the right place - a read or write may span multiple pages, so a single up-front check is insufficient. High memory accesses already have a similar validity check just before the copy_to_user() call, so just make the low memory path fully consistent with that. Reported-by: Jason A. Donenfeld CC: stable@vger.kernel.org Fixes: 148a1bc84398 ("drivers: char: mem: Check {read,write}_kmem() addresses") Signed-off-by: Robin Murphy Signed-off-by: Greg Kroah-Hartman --- drivers/char/mem.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 5bb1985ec484..6d9cc2d39d22 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -381,9 +381,6 @@ static ssize_t read_kmem(struct file *file, char __user *buf, char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ int err = 0; - if (!pfn_valid(PFN_DOWN(p))) - return -EIO; - read = 0; if (p < (unsigned long) high_memory) { low_count = count; @@ -412,6 +409,8 @@ static ssize_t read_kmem(struct file *file, char __user *buf, * by the kernel or data corruption may occur */ kbuf = xlate_dev_kmem_ptr((void *)p); + if (!virt_addr_valid(kbuf)) + return -ENXIO; if (copy_to_user(buf, kbuf, sz)) return -EFAULT; @@ -482,6 +481,8 @@ static ssize_t do_write_kmem(unsigned long p, const char __user *buf, * corruption may occur. */ ptr = xlate_dev_kmem_ptr((void *)p); + if (!virt_addr_valid(ptr)) + return -ENXIO; copied = copy_from_user(ptr, buf, sz); if (copied) { @@ -512,9 +513,6 @@ static ssize_t write_kmem(struct file *file, const char __user *buf, char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ int err = 0; - if (!pfn_valid(PFN_DOWN(p))) - return -EIO; - if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, (unsigned long)high_memory - p); -- cgit v1.2.1 From 0fa2c8eb270413160557babda519aa3c21e2bfaf Mon Sep 17 00:00:00 2001 From: Colin Ian King Date: Fri, 2 Dec 2016 16:23:55 +0000 Subject: ppdev: don't print a free'd string A previous fix of a memory leak now prints the string 'name' that was previously free'd. Fix this by free'ing the string at the end of the function and adding an error exit path for the error conditions. CoverityScan CID#1384523 ("Use after free") Fixes: 2bd362d5f45c1 ("ppdev: fix memory leak") Signed-off-by: Colin Ian King Acked-by: Sudip Mukherjee Signed-off-by: Greg Kroah-Hartman --- drivers/char/ppdev.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'drivers/char') diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c index 02819e0703c8..87885d146dbb 100644 --- a/drivers/char/ppdev.c +++ b/drivers/char/ppdev.c @@ -290,6 +290,7 @@ static int register_device(int minor, struct pp_struct *pp) struct pardevice *pdev = NULL; char *name; struct pardev_cb ppdev_cb; + int rc = 0; name = kasprintf(GFP_KERNEL, CHRDEV "%x", minor); if (name == NULL) @@ -298,8 +299,8 @@ static int register_device(int minor, struct pp_struct *pp) port = parport_find_number(minor); if (!port) { pr_warn("%s: no associated port!\n", name); - kfree(name); - return -ENXIO; + rc = -ENXIO; + goto err; } memset(&ppdev_cb, 0, sizeof(ppdev_cb)); @@ -308,16 +309,18 @@ static int register_device(int minor, struct pp_struct *pp) ppdev_cb.private = pp; pdev = parport_register_dev_model(port, name, &ppdev_cb, minor); parport_put_port(port); - kfree(name); if (!pdev) { pr_warn("%s: failed to register device!\n", name); - return -ENXIO; + rc = -ENXIO; + goto err; } pp->pdev = pdev; dev_dbg(&pdev->dev, "registered pardevice\n"); - return 0; +err: + kfree(name); + return rc; } static enum ieee1284_phase init_phase(int mode) -- cgit v1.2.1