CVE-2024-43840 Information

Description

In the Linux kernel the following vulnerability has been resolved:

bpf arm64: Fix trampoline for BPF_TRAMP_F_CALL_ORIG

When BPF_TRAMP_F_CALL_ORIG is set the trampoline calls __bpf_tramp_enter() and __bpf_tramp_exit() functions passing them the struct bpf_tramp_image im pointer as an argument in R0.

The trampoline generation code uses emit_addr_mov_i64() to emit instructions for moving the bpf_tramp_image address into R0 but emit_addr_mov_i64() assumes the address to be in the vmalloc() space and uses only 48 bits. Because bpf_tramp_image is allocated using kzalloc() its address can use more than 48-bits in this case the trampoline will pass an invalid address to __bpf_tramp_enter/exit() causing a kernel crash.

Fix this by using emit_a64_mov_i64() in place of emit_addr_mov_i64() as it can work with addresses that are greater than 48-bits.

Reference

https://git.kernel.org/stable/c/6d218fcc707d6b2c3616b6cd24b948fd4825cfec https://git.kernel.org/stable/c/19d3c179a37730caf600a97fed3794feac2b197b