The file interpreter is allocated in load_elf_binary, but not freed
in the case interp_elf_ex is NULL.
Add a label “out_allow_write_access” so that the interpreter
will be appropriately released in this case.
This memory leak is catched when kmemleak is enabled in kernel,
the report looks like below:
unreferenced object 0xffff8b6e9fd41400 (size 488):
comm "service", pid 4095, jiffies 4300970844 (age 49.618s)
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
e0 08 be b9 6e 8b ff ff 00 13 04 b7 6e 8b ff ff ....n.......n...
backtrace:
[<00000000eacadaa2>] kmem_cache_alloc+0x164/0x320
[<0000000090fb7bf2>] __alloc_file+0x2a/0x140
[<00000000ff8fab86>] alloc_empty_file+0x4b/0x100
[<000000003ab9b00d>] path_openat+0x4a/0xe20
[<0000000027e3a067>] do_filp_open+0xb9/0x150
[<000000000edebcac>] do_open_execat+0xa6/0x250
[<000000008845564e>] open_exec+0x31/0x60
[<00000000e6e6e1ca>] load_elf_binary+0x1dd/0x1b60
[<000000004515d8f0>] do_execveat_common.isra.39+0xaa0/0x1000
[<000000002ca5e83f>] __x64_sys_execve+0x37/0x40
[<00000000beb519e4>] do_syscall_64+0x56/0xa0
[<000000009cf54d51>] entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: 0693ffebcfe5 ("fs/binfmt_elf.c: allocate less for static executable")
Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx>
---
fs/binfmt_elf.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index fa50e8936f5f..28e75cb45b26 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -907,7 +907,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
interp_elf_ex = kmalloc(sizeof(*interp_elf_ex), GFP_KERNEL);
if (!interp_elf_ex) {
retval = -ENOMEM;
- goto out_free_ph;
+ goto out_allow_write_access;
}
/* Get the exec headers */
@@ -1316,6 +1316,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
out_free_dentry:
kfree(interp_elf_ex);
kfree(interp_elf_phdata);
+out_allow_write_access:
allow_write_access(interpreter);
if (interpreter)
fput(interpreter);
--
2.25.1
