Hi,
I am working with Android 13 and V5.15 kernel. During our development,
I found a memory leak using kmemleak.
Steps I did to find the memleak:
mount -t debugfs debugfs /sys/kernel/debug
echo scan=5 > /sys/kernel/debug/kmemleak
cat /sys/kernel/debug/kmemleak
Stack I got (hundreds of them):
unreferenced object 0xffffff8101d31000 (size 1024):
comm "binder:1357_2", pid 1357, jiffies 4294899464 (age 394.468s)
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:
[<ffffffd327cac060>] crypto_create_tfm_node+0x64/0x228
[<ffffffd3279f8c4c>] fscrypt_prepare_key+0xbc/0x230
[<ffffffd3279f9758>] fscrypt_setup_v1_file_key+0x48c/0x510
[<ffffffd3279f8394>] fscrypt_setup_encryption_info+0x210/0x43c
[<ffffffd3279f8108>] fscrypt_prepare_new_inode+0x128/0x1a4
[<ffffffd327bcc878>] f2fs_new_inode+0x27c/0x89c
[<ffffffd327bce7c4>] f2fs_mkdir+0x78/0x278
[<ffffffd32796a3bc>] vfs_mkdir+0x138/0x204
[<ffffffd32796a108>] do_mkdirat+0x88/0x204
[<ffffffd32796a068>] __arm64_sys_mkdirat+0x40/0x58
[<ffffffd3274be5d4>] invoke_syscall+0x60/0x150
[<ffffffd3274be528>] el0_svc_common+0xc8/0x114
[<ffffffd3274be3f0>] do_el0_svc+0x28/0x98
[<ffffffd328abcf88>] el0_svc+0x28/0x90
[<ffffffd328abcefc>] el0t_64_sync_handler+0x88/0xec
[<ffffffd32741164c>] el0t_64_sync+0x1b8/0x1bc
After checking upstream, I came up with the following:
cff805b1518f fscrypt: fix keyring memory leak on mount failure
But my kernel has this patch. So I continued to dig around this and
saw the function fscrypt_prepare_key in fs/crypto/keysetup.c for
V5.15.
I can't see the pointer tfm being used anywhere or saved, and
smp_store_release doesn't kfree it.
Is smp_store_release doing something with that pointer that makes this
memory leak a false positive?
Any help with this issue would be much appreciated.
Thanks
Lucas Tanure
