bpf/verifier: Do not limit maximum direct offset into arena map

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The verifier currently limits direct offsets into a map to 512MiB
to avoid overflow during pointer arithmetic. However, this prevents
arena maps from using direct addressing instructions to access data
at the end of > 512MiB arena maps. This is necessary when moving
arena globals to the end of the arena instead of the front.

Refactor the verifier code to remove the offset calculation during
direct value access calculations. This is possible because the only
two map types that implement .map_direct_value_addr() are arrays and
arenas, and they both do their own internal checks to ensure the
offset is within bounds.

Adjust selftests that expect the old error. These tests still fail
because the verifier identifies the access as out of bounds for the
map, so change them to expect an "invalid access to map value pointer"
error instead.

Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20251216173325.98465-3-emil@etsalapatis.com

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This commit is contained in:

Emil Tsalapatis 2025-12-16 12:33:22 -05:00 • committed by Andrii Nakryiko

parent 0355911ac0

commit 12a1fe6e12

2 changed files with 2 additions and 7 deletions

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5

kernel/bpf/verifier.c

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4

tools/testing/selftests/bpf/verifier/direct_value_access.c

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