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Jiayuan Chen says: ==================== bpf: Fix array bounds error with may_goto and add selftest Syzbot caught an array out-of-bounds bug [1]. It turns out that when the BPF program runs through do_misc_fixups(), it allocates an extra 8 bytes on the call stack, which eventually causes stack_depth to exceed 512. I was able to reproduce this issue probabilistically by enabling CONFIG_UBSAN=y and disabling CONFIG_BPF_JIT_ALWAYS_ON with the selfttest I provide in second patch(although it doesn't happen every time - I didn't dig deeper into why UBSAN behaves this way). Furthermore, if I set /proc/sys/net/core/bpf_jit_enable to 0 to disable the jit, a panic occurs, and the reason is the same, that bpf_func is assigned an incorrect address. [---[ end trace ]--- [Oops: general protection fault, probably for non-canonical address 0x100f0e0e0d090808: 0000 [#1] PREEMPT SMP NOPTI [Tainted: [W]=WARN, [O]=OOT_MODULE [RIP: 0010:bpf_test_run+0x1d2/0x360 [RSP: 0018:ffffafc7955178a0 EFLAGS: 00010246 [RAX: 100f0e0e0d090808 RBX: ffff8e9fdb2c4100 RCX: 0000000000000018 [RDX: 00000000002b5b18 RSI: ffffafc780497048 RDI: ffff8ea04d601700 [RBP: ffffafc780497000 R08: ffffafc795517a0c R09: 0000000000000000 [R10: 0000000000000000 R11: fefefefefefefeff R12: ffff8ea04d601700 [R13: ffffafc795517928 R14: ffffafc795517928 R15: 0000000000000000 [CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [CR2: 00007f181c064648 CR3: 00000001aa2be003 CR4: 0000000000770ef0 [DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400 [PKRU: 55555554 [Call Trace: [ <TASK> [ ? die_addr+0x36/0x90 [ ? exc_general_protection+0x237/0x430 [ ? asm_exc_general_protection+0x26/0x30 [ ? bpf_test_run+0x1d2/0x360 [ ? bpf_test_run+0x10d/0x360 [ ? __link_object+0x12a/0x1e0 [ ? slab_build_skb+0x23/0x130 [ ? kmem_cache_alloc_noprof+0x2ea/0x3f0 [ ? sk_prot_alloc+0xc2/0x120 [ bpf_prog_test_run_skb+0x21b/0x590 [ __sys_bpf+0x340/0xa80 [ __x64_sys_bpf+0x1e/0x30 --- v2 -> v3: Optimized some code naming and conditional judgment logic. https://lore.kernel.org/bpf/20250213131214.164982-1-mrpre@163.com/T/ v1 -> v2: Directly reject loading programs with a stack size greater than 512 when jit disabled.(Suggested by Alexei Starovoitov) https://lore.kernel.org/bpf/20250212135251.85487-1-mrpre@163.com/T/ ==================== Link: https://patch.msgid.link/20250214091823.46042-1-mrpre@163.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.