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| author | Wang Yufen <wangyufen@huawei.com> | 2022-11-08 13:11:31 +0800 |
|---|---|---|
| committer | Martin KaFai Lau <martin.lau@kernel.org> | 2022-11-08 09:21:35 -0800 |
| commit | eb86559a691cea5fa63e57a03ec3dc9c31e97955 (patch) | |
| tree | 011419a5a708770d91e911b4da26cafab0b95227 /kernel/bpf | |
| parent | a679120edfcf3d63f066f53afd425d51b480e533 (diff) | |
| download | linux-eb86559a691cea5fa63e57a03ec3dc9c31e97955.tar.bz2 | |
bpf: Fix memory leaks in __check_func_call
kmemleak reports this issue:
unreferenced object 0xffff88817139d000 (size 2048):
comm "test_progs", pid 33246, jiffies 4307381979 (age 45851.820s)
hex dump (first 32 bytes):
01 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:
[<0000000045f075f0>] kmalloc_trace+0x27/0xa0
[<0000000098b7c90a>] __check_func_call+0x316/0x1230
[<00000000b4c3c403>] check_helper_call+0x172e/0x4700
[<00000000aa3875b7>] do_check+0x21d8/0x45e0
[<000000001147357b>] do_check_common+0x767/0xaf0
[<00000000b5a595b4>] bpf_check+0x43e3/0x5bc0
[<0000000011e391b1>] bpf_prog_load+0xf26/0x1940
[<0000000007f765c0>] __sys_bpf+0xd2c/0x3650
[<00000000839815d6>] __x64_sys_bpf+0x75/0xc0
[<00000000946ee250>] do_syscall_64+0x3b/0x90
[<0000000000506b7f>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
The root case here is: In function prepare_func_exit(), the callee is
not released in the abnormal scenario after "state->curframe--;". To
fix, move "state->curframe--;" to the very bottom of the function,
right when we free callee and reset frame[] pointer to NULL, as Andrii
suggested.
In addition, function __check_func_call() has a similar problem. In
the abnormal scenario before "state->curframe++;", the callee also
should be released by free_func_state().
Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper")
Fixes: fd978bf7fd31 ("bpf: Add reference tracking to verifier")
Signed-off-by: Wang Yufen <wangyufen@huawei.com>
Link: https://lore.kernel.org/r/1667884291-15666-1-git-send-email-wangyufen@huawei.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 225666307bba..264b3dc714cc 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -6745,11 +6745,11 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn /* Transfer references to the callee */ err = copy_reference_state(callee, caller); if (err) - return err; + goto err_out; err = set_callee_state_cb(env, caller, callee, *insn_idx); if (err) - return err; + goto err_out; clear_caller_saved_regs(env, caller->regs); @@ -6766,6 +6766,11 @@ static int __check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn print_verifier_state(env, callee, true); } return 0; + +err_out: + free_func_state(callee); + state->frame[state->curframe + 1] = NULL; + return err; } int map_set_for_each_callback_args(struct bpf_verifier_env *env, @@ -6979,8 +6984,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) return -EINVAL; } - state->curframe--; - caller = state->frame[state->curframe]; + caller = state->frame[state->curframe - 1]; if (callee->in_callback_fn) { /* enforce R0 return value range [0, 1]. */ struct tnum range = callee->callback_ret_range; @@ -7019,7 +7023,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) } /* clear everything in the callee */ free_func_state(callee); - state->frame[state->curframe + 1] = NULL; + state->frame[state->curframe--] = NULL; return 0; } |