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authorKees Cook <keescook@chromium.org>2022-10-28 19:54:30 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2022-11-01 14:29:16 +0100
commit42378a9ca55347102bbf86708776061d8fe3ece2 (patch)
treee98efcd12f2a79b8ec2e18efeeafdc86f6cdb364 /kernel
parent363a5328f4b0517e59572118ccfb7c626d81dca9 (diff)
bpf, verifier: Fix memory leak in array reallocation for stack state
If an error (NULL) is returned by krealloc(), callers of realloc_array() were setting their allocation pointers to NULL, but on error krealloc() does not touch the original allocation. This would result in a memory resource leak. Instead, free the old allocation on the error handling path. The memory leak information is as follows as also reported by Zhengchao: unreferenced object 0xffff888019801800 (size 256): comm "bpf_repo", pid 6490, jiffies 4294959200 (age 17.170s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000b211474b>] __kmalloc_node_track_caller+0x45/0xc0 [<0000000086712a0b>] krealloc+0x83/0xd0 [<00000000139aab02>] realloc_array+0x82/0xe2 [<00000000b1ca41d1>] grow_stack_state+0xfb/0x186 [<00000000cd6f36d2>] check_mem_access.cold+0x141/0x1341 [<0000000081780455>] do_check_common+0x5358/0xb350 [<0000000015f6b091>] bpf_check.cold+0xc3/0x29d [<000000002973c690>] bpf_prog_load+0x13db/0x2240 [<00000000028d1644>] __sys_bpf+0x1605/0x4ce0 [<00000000053f29bd>] __x64_sys_bpf+0x75/0xb0 [<0000000056fedaf5>] do_syscall_64+0x35/0x80 [<000000002bd58261>] entry_SYSCALL_64_after_hwframe+0x63/0xcd Fixes: c69431aab67a ("bpf: verifier: Improve function state reallocation") Reported-by: Zhengchao Shao <shaozhengchao@huawei.com> Reported-by: Kees Cook <keescook@chromium.org> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Bill Wendling <morbo@google.com> Cc: Lorenz Bauer <oss@lmb.io> Link: https://lore.kernel.org/bpf/20221029025433.2533810-1-keescook@chromium.org
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/verifier.c9
1 files changed, 7 insertions, 2 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 7f0a9f6cb889..dd9019c8b0db 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1027,12 +1027,17 @@ out:
*/
static void *realloc_array(void *arr, size_t old_n, size_t new_n, size_t size)
{
+ void *new_arr;
+
if (!new_n || old_n == new_n)
goto out;
- arr = krealloc_array(arr, new_n, size, GFP_KERNEL);
- if (!arr)
+ new_arr = krealloc_array(arr, new_n, size, GFP_KERNEL);
+ if (!new_arr) {
+ kfree(arr);
return NULL;
+ }
+ arr = new_arr;
if (new_n > old_n)
memset(arr + old_n * size, 0, (new_n - old_n) * size);