An attempt to pass too long module name to, say, rmmod, may
cause an out-of-bounds memory access (as repoted by UBSan):
$ rmmod $(for i in $(seq 0 4200); do echo -ne x; done)
libkmod/libkmod-module.c:1828:8: runtime error: index 4107 out of bounds for type 'char [4096]'
This is because 'snprintf(path, sizeof(path), ...)' may return the
value which exceeds 'sizeof(path)' (which happens when an output
gets truncated). To play it safe, such a suspicious output is
better to be rejected explicitly.
Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Signed-off-by: Dmitry Antipov <dmantipov@xxxxxxxxx>
---
libkmod/libkmod-module.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/libkmod/libkmod-module.c b/libkmod/libkmod-module.c
index 1da64b3..7736b7e 100644
--- a/libkmod/libkmod-module.c
+++ b/libkmod/libkmod-module.c
@@ -1810,6 +1810,10 @@ KMOD_EXPORT int kmod_module_get_initstate(const struct kmod_module *mod)
pathlen = snprintf(path, sizeof(path),
"/sys/module/%s/initstate", mod->name);
+ if (pathlen >= (int)sizeof(path)) {
+ /* Too long path was truncated */
+ return -ENAMETOOLONG;
+ }
fd = open(path, O_RDONLY|O_CLOEXEC);
if (fd < 0) {
err = -errno;
--
2.40.1
