On 1/22/21 2:30 PM, Thiago Jung Bauermann wrote:
Hi Lakshmi, Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx> writes:IMA allocates kernel virtual memory to carry forward the measurement list, from the current kernel to the next kernel on kexec system call, in ima_add_kexec_buffer() function. In error code paths this memory is not freed resulting in memory leak. Free the memory allocated for the IMA measurement list in the error code paths in ima_add_kexec_buffer() function. Signed-off-by: Lakshmi Ramasubramanian <nramas@xxxxxxxxxxxxxxxxxxx> Suggested-by: Tyler Hicks <tyhicks@xxxxxxxxxxxxxxxxxxx> Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list") --- security/integrity/ima/ima_kexec.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c index 121de3e04af2..212145008a01 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -119,12 +119,14 @@ void ima_add_kexec_buffer(struct kimage *image) ret = kexec_add_buffer(&kbuf); if (ret) { pr_err("Error passing over kexec measurement buffer.\n"); + vfree(kexec_buffer); return; }This is a good catch.
Thanks.
ret = arch_ima_add_kexec_buffer(image, kbuf.mem, kexec_segment_size);if (ret) { pr_err("Error passing over kexec measurement buffer.\n"); + vfree(kexec_buffer); return; }But this would cause problems, because the buffer is still there in the kimage and would cause kimage_load_segment() to access invalid memory. There's no function to undo a kexec_add_buffer() to avoid this problem, so I'd suggest just accepting the leak in this case. Fortunately, the current implementations of arch_ima_add_kexec_buffer() are very simple and cannot fail, so this is a theoretical problem.
Agreed. I'll post a new patch with the above change removed. thanks, -lakshmi
