The patch titled
Subject: lib: prevent module unloading if memory is not freed
has been added to the -mm mm-unstable branch. Its filename is
lib-prevent-module-unloading-if-memory-is-not-freed.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/lib-prevent-module-unloading-if-memory-is-not-freed.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Subject: lib: prevent module unloading if memory is not freed
Date: Thu, 21 Mar 2024 09:36:34 -0700
Skip freeing module's data section if there are non-zero allocation tags
because otherwise, once these allocations are freed, the access to their
code tag would cause UAF.
Link: https://lkml.kernel.org/r/20240321163705.3067592-13-surenb@xxxxxxxxxx
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Alex Gaynor <alex.gaynor@xxxxxxxxx>
Cc: Alice Ryhl <aliceryhl@xxxxxxxxxx>
Cc: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
Cc: Benno Lossin <benno.lossin@xxxxxxxxx>
Cc: "Björn Roy Baron" <bjorn3_gh@xxxxxxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Dennis Zhou <dennis@xxxxxxxxxx>
Cc: Gary Guo <gary@xxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Cc: Miguel Ojeda <ojeda@xxxxxxxxxx>
Cc: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Wedson Almeida Filho <wedsonaf@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/codetag.h | 6 +++---
kernel/module/main.c | 27 +++++++++++++++++++--------
lib/codetag.c | 11 ++++++++---
3 files changed, 30 insertions(+), 14 deletions(-)
--- a/include/linux/codetag.h~lib-prevent-module-unloading-if-memory-is-not-freed
+++ a/include/linux/codetag.h
@@ -35,7 +35,7 @@ struct codetag_type_desc {
size_t tag_size;
void (*module_load)(struct codetag_type *cttype,
struct codetag_module *cmod);
- void (*module_unload)(struct codetag_type *cttype,
+ bool (*module_unload)(struct codetag_type *cttype,
struct codetag_module *cmod);
};
@@ -71,10 +71,10 @@ codetag_register_type(const struct codet
#if defined(CONFIG_CODE_TAGGING) && defined(CONFIG_MODULES)
void codetag_load_module(struct module *mod);
-void codetag_unload_module(struct module *mod);
+bool codetag_unload_module(struct module *mod);
#else
static inline void codetag_load_module(struct module *mod) {}
-static inline void codetag_unload_module(struct module *mod) {}
+static inline bool codetag_unload_module(struct module *mod) { return true; }
#endif
#endif /* _LINUX_CODETAG_H */
--- a/kernel/module/main.c~lib-prevent-module-unloading-if-memory-is-not-freed
+++ a/kernel/module/main.c
@@ -1211,15 +1211,19 @@ static void *module_memory_alloc(unsigne
return module_alloc(size);
}
-static void module_memory_free(void *ptr, enum mod_mem_type type)
+static void module_memory_free(void *ptr, enum mod_mem_type type,
+ bool unload_codetags)
{
+ if (!unload_codetags && mod_mem_type_is_core_data(type))
+ return;
+
if (mod_mem_use_vmalloc(type))
vfree(ptr);
else
module_memfree(ptr);
}
-static void free_mod_mem(struct module *mod)
+static void free_mod_mem(struct module *mod, bool unload_codetags)
{
for_each_mod_mem_type(type) {
struct module_memory *mod_mem = &mod->mem[type];
@@ -1230,20 +1234,27 @@ static void free_mod_mem(struct module *
/* Free lock-classes; relies on the preceding sync_rcu(). */
lockdep_free_key_range(mod_mem->base, mod_mem->size);
if (mod_mem->size)
- module_memory_free(mod_mem->base, type);
+ module_memory_free(mod_mem->base, type,
+ unload_codetags);
}
/* MOD_DATA hosts mod, so free it at last */
lockdep_free_key_range(mod->mem[MOD_DATA].base, mod->mem[MOD_DATA].size);
- module_memory_free(mod->mem[MOD_DATA].base, MOD_DATA);
+ module_memory_free(mod->mem[MOD_DATA].base, MOD_DATA, unload_codetags);
}
/* Free a module, remove from lists, etc. */
static void free_module(struct module *mod)
{
+ bool unload_codetags;
+
trace_module_free(mod);
- codetag_unload_module(mod);
+ unload_codetags = codetag_unload_module(mod);
+ if (!unload_codetags)
+ pr_warn("%s: memory allocation(s) from the module still alive, cannot unload cleanly\n",
+ mod->name);
+
mod_sysfs_teardown(mod);
/*
@@ -1285,7 +1296,7 @@ static void free_module(struct module *m
kfree(mod->args);
percpu_modfree(mod);
- free_mod_mem(mod);
+ free_mod_mem(mod, unload_codetags);
}
void *__symbol_get(const char *symbol)
@@ -2298,7 +2309,7 @@ static int move_module(struct module *mo
return 0;
out_enomem:
for (t--; t >= 0; t--)
- module_memory_free(mod->mem[t].base, t);
+ module_memory_free(mod->mem[t].base, t, true);
return ret;
}
@@ -2428,7 +2439,7 @@ static void module_deallocate(struct mod
percpu_modfree(mod);
module_arch_freeing_init(mod);
- free_mod_mem(mod);
+ free_mod_mem(mod, true);
}
int __weak module_finalize(const Elf_Ehdr *hdr,
--- a/lib/codetag.c~lib-prevent-module-unloading-if-memory-is-not-freed
+++ a/lib/codetag.c
@@ -5,6 +5,7 @@
#include <linux/module.h>
#include <linux/seq_buf.h>
#include <linux/slab.h>
+#include <linux/vmalloc.h>
struct codetag_type {
struct list_head link;
@@ -206,12 +207,13 @@ void codetag_load_module(struct module *
mutex_unlock(&codetag_lock);
}
-void codetag_unload_module(struct module *mod)
+bool codetag_unload_module(struct module *mod)
{
struct codetag_type *cttype;
+ bool unload_ok = true;
if (!mod)
- return;
+ return true;
mutex_lock(&codetag_lock);
list_for_each_entry(cttype, &codetag_types, link) {
@@ -228,7 +230,8 @@ void codetag_unload_module(struct module
}
if (found) {
if (cttype->desc.module_unload)
- cttype->desc.module_unload(cttype, cmod);
+ if (!cttype->desc.module_unload(cttype, cmod))
+ unload_ok = false;
cttype->count -= range_size(cttype, &cmod->range);
idr_remove(&cttype->mod_idr, mod_id);
@@ -237,6 +240,8 @@ void codetag_unload_module(struct module
up_write(&cttype->mod_lock);
}
mutex_unlock(&codetag_lock);
+
+ return unload_ok;
}
#else /* CONFIG_MODULES */
_
Patches currently in -mm which might be from surenb@xxxxxxxxxx are
mm-introduce-slabobj_ext-to-support-slab-object-extensions.patch
mm-introduce-__gfp_no_obj_ext-flag-to-selectively-prevent-slabobj_ext-creation.patch
mm-slab-introduce-slab_no_obj_ext-to-avoid-obj_ext-creation.patch
slab-objext-introduce-objext_flags-as-extension-to-page_memcg_data_flags.patch
lib-code-tagging-framework.patch
lib-code-tagging-module-support.patch
lib-prevent-module-unloading-if-memory-is-not-freed.patch
lib-add-allocation-tagging-support-for-memory-allocation-profiling.patch
lib-introduce-support-for-page-allocation-tagging.patch
lib-introduce-early-boot-parameter-to-avoid-page_ext-memory-overhead.patch
mm-percpu-increase-percpu_module_reserve-to-accommodate-allocation-tags.patch
change-alloc_pages-name-in-dma_map_ops-to-avoid-name-conflicts.patch
mm-enable-page-allocation-tagging.patch
mm-create-new-codetag-references-during-page-splitting.patch
mm-fix-non-compound-multi-order-memory-accounting-in-__free_pages.patch
mm-page_ext-enable-early_page_ext-when-config_mem_alloc_profiling_debug=y.patch
lib-add-codetag-reference-into-slabobj_ext.patch
mm-slab-add-allocation-accounting-into-slab-allocation-and-free-paths.patch
mm-slab-enable-slab-allocation-tagging-for-kmalloc-and-friends.patch
mm-percpu-enable-per-cpu-allocation-tagging.patch
lib-add-memory-allocations-report-in-show_mem.patch
codetag-debug-skip-objext-checking-when-its-for-objext-itself.patch
codetag-debug-mark-codetags-for-reserved-pages-as-empty.patch
codetag-debug-introduce-objexts_alloc_fail-to-mark-failed-slab_ext-allocations.patch
