On ppc64, When a non-nul terminated string is passed as an argument to
the mount(2) syscall, copy_mount_string() ends up allocating 64k (the
PAGE_SIZE on ppc64) worth of space for holding the string in kernel's
address space.
Later, in set_precision() (invoked indirectly by get_fs_type()), we end
up assigning 65535 as the value to 'struct printf_spec'->precision
member. This field has a width of 16 bits and hence a truncated version
of the original value ends up being assigned. This causes the
"WARN_ONCE(spec->precision != prec, "precision %d too large", prec)"
statement inside set_precision() to be executed.
This commit fixes the bug by validating the length of the "filesystem
type" argument passed to get_fs_type() function.
Signed-off-by: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
Reported-by: Abdul Haleem <abdhalee@xxxxxxxxxxxxxxxxxx>
Suggested-by: Joe Perches <joe@xxxxxxxxxxx>
---
fs/filesystems.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/filesystems.c b/fs/filesystems.c
index a920ad2..8e309d3 100644
--- a/fs/filesystems.c
+++ b/fs/filesystems.c
@@ -275,6 +275,9 @@ struct file_system_type *get_fs_type(const char *name)
const char *dot = strchr(name, '.');
int len = dot ? dot - name : strlen(name);
+ if (len >= PATH_MAX)
+ return NULL;
+
fs = __get_fs_type(name, len);
if (!fs && (request_module("fs-%.*s", len, name) == 0)) {
fs = __get_fs_type(name, len);
--
2.9.4
