diff options
| author | Neal Cardwell | 2012-12-09 11:09:54 +0000 |
|---|---|---|
| committer | David S. Miller | 2012-12-09 19:00:48 -0500 |
| commit | 5e1f54201cb481f40a04bc47e1bc8c093a189e23 (patch) | |
| tree | f5fa04ab4f52467197692f6ddf3cb56d5908595e /net/ipv4 | |
| parent | f67caec9068cee426ec23cf9005a1dee2ecad187 (diff) | |
inet_diag: validate port comparison byte code to prevent unsafe reads
Add logic to verify that a port comparison byte code operation
actually has the second inet_diag_bc_op from which we read the port
for such operations.
Previously the code blindly referenced op[1] without first checking
whether a second inet_diag_bc_op struct could fit there. So a
malicious user could make the kernel read 4 bytes beyond the end of
the bytecode array by claiming to have a whole port comparison byte
code (2 inet_diag_bc_op structs) when in fact the bytecode was not
long enough to hold both.
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/inet_diag.c | 31 |
1 files changed, 24 insertions, 7 deletions
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c index 95f1a458371d..e23e16dc501d 100644 --- a/net/ipv4/inet_diag.c +++ b/net/ipv4/inet_diag.c @@ -557,6 +557,17 @@ static bool valid_hostcond(const struct inet_diag_bc_op *op, int len, return true; } +/* Validate a port comparison operator. */ +static inline bool valid_port_comparison(const struct inet_diag_bc_op *op, + int len, int *min_len) +{ + /* Port comparisons put the port in a follow-on inet_diag_bc_op. */ + *min_len += sizeof(struct inet_diag_bc_op); + if (len < *min_len) + return false; + return true; +} + static int inet_diag_bc_audit(const void *bytecode, int bytecode_len) { const void *bc = bytecode; @@ -572,24 +583,30 @@ static int inet_diag_bc_audit(const void *bytecode, int bytecode_len) case INET_DIAG_BC_D_COND: if (!valid_hostcond(bc, len, &min_len)) return -EINVAL; - /* fall through */ - case INET_DIAG_BC_AUTO: + break; case INET_DIAG_BC_S_GE: case INET_DIAG_BC_S_LE: case INET_DIAG_BC_D_GE: case INET_DIAG_BC_D_LE: - case INET_DIAG_BC_JMP: - if (op->no < min_len || op->no > len + 4 || op->no & 3) - return -EINVAL; - if (op->no < len && - !valid_cc(bytecode, bytecode_len, len - op->no)) + if (!valid_port_comparison(bc, len, &min_len)) return -EINVAL; break; + case INET_DIAG_BC_AUTO: + case INET_DIAG_BC_JMP: case INET_DIAG_BC_NOP: break; default: return -EINVAL; } + + if (op->code != INET_DIAG_BC_NOP) { + if (op->no < min_len || op->no > len + 4 || op->no & 3) + return -EINVAL; + if (op->no < len && + !valid_cc(bytecode, bytecode_len, len - op->no)) + return -EINVAL; + } + if (op->yes < min_len || op->yes > len + 4 || op->yes & 3) return -EINVAL; bc += op->yes; |