[59/93] devmem: check vmalloc address on kmem read/write
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From: Greg KH on 19 Feb 2010 12:10 2.6.32-stable review patch. If anyone has any objections, please let us know. ------------------ From: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> commit 325fda71d0badc1073dc59f12a948f24ff05796a [ cebbert(a)redhat.com : backport to 2.6.32 ] devmem: check vmalloc address on kmem read/write Otherwise vmalloc_to_page() will BUG(). This also makes the kmem read/write implementation aligned with mem(4): "References to nonexistent locations cause errors to be returned." Here we return -ENXIO (inspired by Hugh) if no bytes have been transfered to/from user space, otherwise return partial read/write results. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> Signed-off-by: Wu Fengguang <fengguang.wu(a)intel.com> Cc: Greg Kroah-Hartman <gregkh(a)suse.de> Cc: Hugh Dickins <hugh.dickins(a)tiscali.co.uk> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Chuck Ebbert <cebbert(a)redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de> --- drivers/char/mem.c | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-) --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -421,6 +421,7 @@ static ssize_t read_kmem(struct file *fi unsigned long p = *ppos; ssize_t low_count, read, sz; char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */ + int err = 0; read = 0; if (p < (unsigned long) high_memory) { @@ -469,12 +470,16 @@ static ssize_t read_kmem(struct file *fi while (count > 0) { int len = size_inside_page(p, count); + if (!is_vmalloc_or_module_addr((void *)p)) { + err = -ENXIO; + break; + } len = vread(kbuf, (char *)p, len); if (!len) break; if (copy_to_user(buf, kbuf, len)) { - free_page((unsigned long)kbuf); - return -EFAULT; + err = -EFAULT; + break; } count -= len; buf += len; @@ -483,8 +488,8 @@ static ssize_t read_kmem(struct file *fi } free_page((unsigned long)kbuf); } - *ppos = p; - return read; + *ppos = p; + return read ? read : err; } @@ -553,6 +558,7 @@ static ssize_t write_kmem(struct file * ssize_t virtr = 0; ssize_t written; char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ + int err = 0; if (p < (unsigned long) high_memory) { @@ -576,13 +582,15 @@ static ssize_t write_kmem(struct file * while (count > 0) { int len = size_inside_page(p, count); + if (!is_vmalloc_or_module_addr((void *)p)) { + err = -ENXIO; + break; + } if (len) { written = copy_from_user(kbuf, buf, len); if (written) { - if (wrote + virtr) - break; - free_page((unsigned long)kbuf); - return -EFAULT; + err = -EFAULT; + break; } } len = vwrite(kbuf, (char *)p, len); @@ -594,8 +602,8 @@ static ssize_t write_kmem(struct file * free_page((unsigned long)kbuf); } - *ppos = p; - return virtr + wrote; + *ppos = p; + return virtr + wrote ? : err; } #endif -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |