From: KAMEZAWA Hiroyuki 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. CC: Greg Kroah-Hartman CC: Hugh Dickins Signed-off-by: KAMEZAWA Hiroyuki Signed-off-by: Wu Fengguang --- drivers/char/mem.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) --- linux-mm.orig/drivers/char/mem.c 2009-09-16 10:48:16.000000000 +0800 +++ linux-mm/drivers/char/mem.c 2009-09-16 10:57:13.000000000 +0800 @@ -396,6 +396,7 @@ 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) { @@ -442,12 +443,16 @@ static ssize_t read_kmem(struct file *fi return -ENOMEM; while (count > 0) { sz = size_inside_page(p, count); + if (!is_vmalloc_or_module_addr((void *)p)) { + err = -ENXIO; + break; + } sz = vread(kbuf, (char *)p, sz); if (!sz) break; if (copy_to_user(buf, kbuf, sz)) { - free_page((unsigned long)kbuf); - return -EFAULT; + err = -EFAULT; + break; } count -= sz; buf += sz; @@ -457,7 +462,7 @@ static ssize_t read_kmem(struct file *fi free_page((unsigned long)kbuf); } *ppos = p; - return read; + return read ? read : err; } @@ -521,6 +526,7 @@ static ssize_t write_kmem(struct file * ssize_t wrote = 0; ssize_t virtr = 0; char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */ + int err = 0; if (p < (unsigned long) high_memory) { unsigned long to_write = min_t(unsigned long, count, @@ -541,12 +547,14 @@ static ssize_t write_kmem(struct file * unsigned long sz = size_inside_page(p, count); unsigned long n; + if (!is_vmalloc_or_module_addr((void *)p)) { + err = -ENXIO; + break; + } n = copy_from_user(kbuf, buf, sz); if (n) { - if (wrote + virtr) - break; - free_page((unsigned long)kbuf); - return -EFAULT; + err = -EFAULT; + break; } vwrite(kbuf, (char *)p, sz); count -= sz; @@ -558,7 +566,7 @@ static ssize_t write_kmem(struct file * } *ppos = p; - return virtr + wrote; + return virtr + wrote ? : err; } #endif -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/