module: Fix memory deallocation on error path in move_module()

The function move_module() uses the variable t to track how many memory
types it has allocated and consequently how many should be freed if an
error occurs.

The variable is initially set to 0 and is updated when a call to
module_memory_alloc() fails. However, move_module() can fail for other
reasons as well, in which case t remains set to 0 and no memory is freed.

Fix the problem by initializing t to MOD_MEM_NUM_TYPES. Additionally, make
the deallocation loop more robust by not relying on the mod_mem_type_t enum
having a signed integer as its underlying type.

Fixes: c7ee8aebf6c0 ("module: add stop-grap sanity check on module memcpy()")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Daniel Gomez <da.gomez@samsung.com>
Link: https://lore.kernel.org/r/20250618122730.51324-2-petr.pavlu@suse.com
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>
Message-ID: <20250618122730.51324-2-petr.pavlu@suse.com>

diff --git a/kernel/module/main.c b/kernel/module/main.c
index 413ac6ea37021bc8ae260f624ca2745ed85333fc..9ac994b2f354a04ebf65f4924796f80012188b15 100644 (file)
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -2697,7 +2697,7 @@ static int find_module_sections(struct module *mod, struct load_info *info)
 static int move_module(struct module *mod, struct load_info *info)
 {
        int i;
-       enum mod_mem_type t = 0;
+       enum mod_mem_type t = MOD_MEM_NUM_TYPES;
        int ret = -ENOMEM;
        bool codetag_section_found = false;
 
@@ -2776,7 +2776,7 @@ static int move_module(struct module *mod, struct load_info *info)
        return 0;
 out_err:
        module_memory_restore_rox(mod);
-       for (t--; t >= 0; t--)
+       while (t--)
                module_memory_free(mod, t);
        if (codetag_section_found)
                codetag_free_module_sections(mod);