From: Samuel Mendoza-Jonas samjonas@amazon.com
The 4.14 backport of 9d7eceede ("bpf: restrict unknown scalars of mixed signed bounds for unprivileged") adds the PTR_TO_MAP_VALUE check to the wrong location in adjust_ptr_min_max_vals(), most likely because 4.14 doesn't include the commit that updates the if-statement to a switch-statement (aad2eeaf4 "bpf: Simplify ptr_min_max_vals adjustment").
Move the check to the proper location in adjust_ptr_min_max_vals().
Fixes: 17efa65350c5a ("bpf: restrict unknown scalars of mixed signed bounds for unprivileged") Signed-off-by: Samuel Mendoza-Jonas samjonas@amazon.com Reviewed-by: Frank van der Linden fllinden@amazon.com Reviewed-by: Ethan Chen yishache@amazon.com Acked-by: Yonghong Song yhs@fb.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/bpf/verifier.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
--- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2204,6 +2204,13 @@ static int adjust_ptr_min_max_vals(struc dst); return -EACCES; } + if (ptr_reg->type == PTR_TO_MAP_VALUE) { + if (!env->allow_ptr_leaks && !known && (smin_val < 0) != (smax_val < 0)) { + verbose("R%d has unknown scalar with mixed signed bounds, pointer arithmetic with it prohibited for !root\n", + off_reg == dst_reg ? dst : src); + return -EACCES; + } + }
/* In case of 'scalar += pointer', dst_reg inherits pointer type and id. * The id may be overwritten later if we create a new variable offset. @@ -2349,13 +2356,6 @@ static int adjust_ptr_min_max_vals(struc verbose("R%d bitwise operator %s on pointer prohibited\n", dst, bpf_alu_string[opcode >> 4]); return -EACCES; - case PTR_TO_MAP_VALUE: - if (!env->allow_ptr_leaks && !known && (smin_val < 0) != (smax_val < 0)) { - verbose("R%d has unknown scalar with mixed signed bounds, pointer arithmetic with it prohibited for !root\n", - off_reg == dst_reg ? dst : src); - return -EACCES; - } - /* fall-through */ default: /* other operators (e.g. MUL,LSH) produce non-pointer results */ if (!env->allow_ptr_leaks)