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| author | Markos Chandras <markos.chandras@imgtec.com> | 2014-06-25 10:37:21 +0200 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2014-06-26 11:48:22 +0200 |
| commit | 95782bf434437b3292f5cb9ce21b53bdbc1beda1 (patch) | |
| tree | df217b9e4d2a4ec7ded37d7d3aea6c34d547e8e9 /arch/mips/net/bpf_jit.c | |
| parent | MIPS: bpf: Drop update_on_xread and always initialize the X register (diff) | |
| download | linux-95782bf434437b3292f5cb9ce21b53bdbc1beda1.tar.xz linux-95782bf434437b3292f5cb9ce21b53bdbc1beda1.zip | |
MIPS: BPF: Prevent kernel fall over for >=32bit shifts
Remove BUG_ON() if the shift immediate is >=32 to avoid kernel crashes
due to malicious user input. If the shift immediate is >= 32,
we simply load the destination register with 0 since only
32-bit instructions are used by JIT so this will do the
correct thing even on MIPS64.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Daniel Borkmann <dborkman@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: netdev@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7179/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/net/bpf_jit.c')
| -rw-r--r-- | arch/mips/net/bpf_jit.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/arch/mips/net/bpf_jit.c b/arch/mips/net/bpf_jit.c index 1bcd599d9971..9476e7f061a1 100644 --- a/arch/mips/net/bpf_jit.c +++ b/arch/mips/net/bpf_jit.c @@ -151,6 +151,8 @@ static inline int optimize_div(u32 *k) return 0; } +static inline void emit_jit_reg_move(ptr dst, ptr src, struct jit_ctx *ctx); + /* Simply emit the instruction if the JIT memory space has been allocated */ #define emit_instr(ctx, func, ...) \ do { \ @@ -309,8 +311,11 @@ static inline void emit_sll(unsigned int dst, unsigned int src, unsigned int sa, struct jit_ctx *ctx) { /* sa is 5-bits long */ - BUG_ON(sa >= BIT(5)); - emit_instr(ctx, sll, dst, src, sa); + if (sa >= BIT(5)) + /* Shifting >= 32 results in zero */ + emit_jit_reg_move(dst, r_zero, ctx); + else + emit_instr(ctx, sll, dst, src, sa); } static inline void emit_srlv(unsigned int dst, unsigned int src, @@ -323,8 +328,11 @@ static inline void emit_srl(unsigned int dst, unsigned int src, unsigned int sa, struct jit_ctx *ctx) { /* sa is 5-bits long */ - BUG_ON(sa >= BIT(5)); - emit_instr(ctx, srl, dst, src, sa); + if (sa >= BIT(5)) + /* Shifting >= 32 results in zero */ + emit_jit_reg_move(dst, r_zero, ctx); + else + emit_instr(ctx, srl, dst, src, sa); } static inline void emit_slt(unsigned int dst, unsigned int src1, |