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Commit 7e9f794

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Daniil Dulovborkmann
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xdp: Remove WARN() from __xdp_reg_mem_model()
syzkaller reports a warning in __xdp_reg_mem_model(). The warning occurs only if __mem_id_init_hash_table() returns an error. It returns the error in two cases: 1. memory allocation fails; 2. rhashtable_init() fails when some fields of rhashtable_params struct are not initialized properly. The second case cannot happen since there is a static const rhashtable_params struct with valid fields. So, warning is only triggered when there is a problem with memory allocation. Thus, there is no sense in using WARN() to handle this error and it can be safely removed. WARNING: CPU: 0 PID: 5065 at net/core/xdp.c:299 __xdp_reg_mem_model+0x2d9/0x650 net/core/xdp.c:299 CPU: 0 PID: 5065 Comm: syz-executor883 Not tainted 6.8.0-syzkaller-05271-gf99c5f563c17 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 RIP: 0010:__xdp_reg_mem_model+0x2d9/0x650 net/core/xdp.c:299 Call Trace: xdp_reg_mem_model+0x22/0x40 net/core/xdp.c:344 xdp_test_run_setup net/bpf/test_run.c:188 [inline] bpf_test_run_xdp_live+0x365/0x1e90 net/bpf/test_run.c:377 bpf_prog_test_run_xdp+0x813/0x11b0 net/bpf/test_run.c:1267 bpf_prog_test_run+0x33a/0x3b0 kernel/bpf/syscall.c:4240 __sys_bpf+0x48d/0x810 kernel/bpf/syscall.c:5649 __do_sys_bpf kernel/bpf/syscall.c:5738 [inline] __se_sys_bpf kernel/bpf/syscall.c:5736 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5736 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x6d/0x75 Found by Linux Verification Center (linuxtesting.org) with syzkaller. Fixes: 8d5d885 ("xdp: rhashtable with allocator ID to pointer mapping") Signed-off-by: Daniil Dulov <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Acked-by: Jesper Dangaard Brouer <[email protected]> Link: https://lore.kernel.org/all/[email protected] Link: https://lore.kernel.org/bpf/[email protected]
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net/core/xdp.c

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -295,10 +295,8 @@ static struct xdp_mem_allocator *__xdp_reg_mem_model(struct xdp_mem_info *mem,
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mutex_lock(&mem_id_lock);
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ret = __mem_id_init_hash_table();
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mutex_unlock(&mem_id_lock);
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if (ret < 0) {
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WARN_ON(1);
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if (ret < 0)
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return ERR_PTR(ret);
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}
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}
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xdp_alloc = kzalloc(sizeof(*xdp_alloc), gfp);

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