From: Oleg Drokin <gr...@linuxhacker.ru> strncpy_from_user could return negative values on error, so need to take those into account. Since ll_getname is used to get a single component name from userspace to transfer to server as-is, there's no need to allocate 4k buffer as done by __getname. Allocate NAME_MAX+1 buffer instead to ensure we have enough for a null terminated max valid length buffer.
This was discovered by Al Viro in https://lkml.org/lkml/2015/4/11/243 Signed-off-by: Oleg Drokin <gr...@linuxhacker.ru> --- drivers/staging/lustre/lustre/llite/dir.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/drivers/staging/lustre/lustre/llite/dir.c b/drivers/staging/lustre/lustre/llite/dir.c index 87a042c..e0b9043 100644 --- a/drivers/staging/lustre/lustre/llite/dir.c +++ b/drivers/staging/lustre/lustre/llite/dir.c @@ -1213,29 +1213,31 @@ out: return rc; } -static char * -ll_getname(const char __user *filename) +/* This function tries to get a single name component, + * to send to the server. No actual path traversal involved, + * so we limit to NAME_MAX */ +static char *ll_getname(const char __user *filename) { int ret = 0, len; - char *tmp = __getname(); + char *tmp = kzalloc(NAME_MAX + 1, GFP_KERNEL); if (!tmp) return ERR_PTR(-ENOMEM); - len = strncpy_from_user(tmp, filename, PATH_MAX); - if (len == 0) + len = strncpy_from_user(tmp, filename, NAME_MAX); + if (len < 0) + ret = len; + else if (len == 0) ret = -ENOENT; - else if (len > PATH_MAX) - ret = -ENAMETOOLONG; if (ret) { - __putname(tmp); + kfree(tmp); tmp = ERR_PTR(ret); } return tmp; } -#define ll_putname(filename) __putname(filename) +#define ll_putname(filename) kfree(filename) static long ll_dir_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { -- 2.1.0 _______________________________________________ devel mailing list de...@linuxdriverproject.org http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
