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bpf: Fix backport of "bpf: restrict unknown scalars of mixed signed bounds for unprivileged" 

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: 17efa65350 ("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>
This commit is contained in:
Samuel Mendoza-Jonas 2021-05-01 18:05:05 +00:00 committed by Greg Kroah-Hartman
parent 5e6f537bb9
commit 33f987529f
1 changed files with 7 additions and 7 deletions
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14
kernel/bpf/verifier.c
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@ -2204,6 +2204,13 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
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(struct bpf_verifier_env *env,
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)