# added Roland mcgrathr@chromium in CC for asm-generic/syscall.h
I modified my patch based on Will's comments. Speaking of arm, i + n is checked against SYSCALL_MAX_ARGS (== 7), but it seems that the kernel code assumes that the current max number of arguments would be 6. For example, SYSCALL_DEFINEn are defined from 0 to 6. Am i wrong?
Changes: * added a patch to arm as well * added a patch to asm-generic/syscall.h; corrected the description on syscall_get_arguments() and syscall_put_arguments() * removed portion of commit message which referred to asm-generic/syscall.h in arm64
AKASHI Takahiro (3): arm64: check for number of arguments in syscall_get/set_arguments() arm: check for number of arguments in syscall_get/set_arguments() asm-generic: syscall_get/set_arguments accept zero for number of arguments
arch/arm/include/asm/syscall.h | 6 ++++++ arch/arm64/include/asm/syscall.h | 6 ++++++ include/asm-generic/syscall.h | 4 ++-- 3 files changed, 14 insertions(+), 2 deletions(-)
In ftrace_syscall_enter(), syscall_get_arguments(..., 0, n, ...) if (i == 0) { <handle orig_x0> ...; n--;} memcpy(..., n * sizeof(args[0])); If 'number of arguments(n)' is zero and 'argument index(i)' is also zero in syscall_get_arguments(), none of arguments should be copied by memcpy(). Otherwise 'n--' can be a big positive number and unexpected amount of data will be copied. Tracing system calls which take no argument, say sync(void), may hit this case and eventually make the system corrupted. This patch fixes the issue both in syscall_get_arguments() and syscall_set_arguments().
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org --- arch/arm64/include/asm/syscall.h | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/arm64/include/asm/syscall.h b/arch/arm64/include/asm/syscall.h index c89821f..01bb8cc 100644 --- a/arch/arm64/include/asm/syscall.h +++ b/arch/arm64/include/asm/syscall.h @@ -63,6 +63,9 @@ static inline void syscall_get_arguments(struct task_struct *task, unsigned int i, unsigned int n, unsigned long *args) { + if (n == 0) + return; + if (i + n > SYSCALL_MAX_ARGS) { unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i; unsigned int n_bad = n + i - SYSCALL_MAX_ARGS; @@ -86,6 +89,9 @@ static inline void syscall_set_arguments(struct task_struct *task, unsigned int i, unsigned int n, const unsigned long *args) { + if (n == 0) + return; + if (i + n > SYSCALL_MAX_ARGS) { pr_warning("%s called with max args %d, handling only %d\n", __func__, i + n, SYSCALL_MAX_ARGS);
On Thu, Oct 03, 2013 at 06:47:44AM +0100, AKASHI Takahiro wrote:
In ftrace_syscall_enter(), syscall_get_arguments(..., 0, n, ...) if (i == 0) { <handle orig_x0> ...; n--;} memcpy(..., n * sizeof(args[0])); If 'number of arguments(n)' is zero and 'argument index(i)' is also zero in syscall_get_arguments(), none of arguments should be copied by memcpy(). Otherwise 'n--' can be a big positive number and unexpected amount of data will be copied. Tracing system calls which take no argument, say sync(void), may hit this case and eventually make the system corrupted. This patch fixes the issue both in syscall_get_arguments() and syscall_set_arguments().
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org
Acked-by: Will Deacon will.deacon@arm.com
Cheers,
Will
In ftrace_syscall_enter(), syscall_get_arguments(..., 0, n, ...) if (i == 0) { <handle ORIG_r0> ...; n--;} memcpy(..., n * sizeof(args[0])); If 'number of arguments(n)' is zero and 'argument index(i)' is also zero in syscall_get_arguments(), none of arguments should be copied by memcpy(). Otherwise 'n--' can be a big positive number and unexpected amount of data will be copied. Tracing system calls which take no argument, say sync(void), may hit this case and eventually make the system corrupted. This patch fixes the issue both in syscall_get_arguments() and syscall_set_arguments().
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org --- arch/arm/include/asm/syscall.h | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h index f1d96d4..73ddd72 100644 --- a/arch/arm/include/asm/syscall.h +++ b/arch/arm/include/asm/syscall.h @@ -57,6 +57,9 @@ static inline void syscall_get_arguments(struct task_struct *task, unsigned int i, unsigned int n, unsigned long *args) { + if (n == 0) + return; + if (i + n > SYSCALL_MAX_ARGS) { unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i; unsigned int n_bad = n + i - SYSCALL_MAX_ARGS; @@ -81,6 +84,9 @@ static inline void syscall_set_arguments(struct task_struct *task, unsigned int i, unsigned int n, const unsigned long *args) { + if (n == 0) + return; + if (i + n > SYSCALL_MAX_ARGS) { pr_warning("%s called with max args %d, handling only %d\n", __func__, i + n, SYSCALL_MAX_ARGS);
On Thu, Oct 03, 2013 at 06:47:45AM +0100, AKASHI Takahiro wrote:
In ftrace_syscall_enter(), syscall_get_arguments(..., 0, n, ...) if (i == 0) { <handle ORIG_r0> ...; n--;} memcpy(..., n * sizeof(args[0])); If 'number of arguments(n)' is zero and 'argument index(i)' is also zero in syscall_get_arguments(), none of arguments should be copied by memcpy(). Otherwise 'n--' can be a big positive number and unexpected amount of data will be copied. Tracing system calls which take no argument, say sync(void), may hit this case and eventually make the system corrupted. This patch fixes the issue both in syscall_get_arguments() and syscall_set_arguments().
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org
arch/arm/include/asm/syscall.h | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h index f1d96d4..73ddd72 100644 --- a/arch/arm/include/asm/syscall.h +++ b/arch/arm/include/asm/syscall.h @@ -57,6 +57,9 @@ static inline void syscall_get_arguments(struct task_struct *task, unsigned int i, unsigned int n, unsigned long *args) {
- if (n == 0)
return;- if (i + n > SYSCALL_MAX_ARGS) { unsigned long *args_bad = args + SYSCALL_MAX_ARGS - i; unsigned int n_bad = n + i - SYSCALL_MAX_ARGS;
@@ -81,6 +84,9 @@ static inline void syscall_set_arguments(struct task_struct *task, unsigned int i, unsigned int n, const unsigned long *args) {
- if (n == 0)
return;- if (i + n > SYSCALL_MAX_ARGS) { pr_warning("%s called with max args %d, handling only %d\n", __func__, i + n, SYSCALL_MAX_ARGS);
Acked-by: Will Deacon will.deacon@arm.com
Please can you put this into the patch system, with a CC stable tag?
Will
There is a possibility of calling syscall_get_arguments() with zero as 'number of arguments(n)' in ftrace_syscall_enter(). The comments in syscall_get_argumets() as well as syscall_set_arugments() are corrected to clarify that.
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org --- include/asm-generic/syscall.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h index 5b09392..49b35ab 100644 --- a/include/asm-generic/syscall.h +++ b/include/asm-generic/syscall.h @@ -106,7 +106,7 @@ void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs, * @task: task of interest, must be blocked * @regs: task_pt_regs() of @task * @i: argument index [0,5] - * @n: number of arguments; n+i must be [1,6]. + * @n: number of arguments; n+i must be [0,6]. * @args: array filled with argument values * * Fetches @n arguments to the system call starting with the @i'th argument @@ -126,7 +126,7 @@ void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs, * @task: task of interest, must be in system call entry tracing * @regs: task_pt_regs() of @task * @i: argument index [0,5] - * @n: number of arguments; n+i must be [1,6]. + * @n: number of arguments; n+i must be [0,6]. * @args: array of argument values to store * * Changes @n arguments to the system call starting with the @i'th argument.
[extending CC list to add the ftrace guys]
On Thu, Oct 03, 2013 at 06:47:46AM +0100, AKASHI Takahiro wrote:
There is a possibility of calling syscall_get_arguments() with zero as 'number of arguments(n)' in ftrace_syscall_enter(). The comments in syscall_get_argumets() as well as syscall_set_arugments() are corrected to clarify that.
Probably also worth mentioning that all architectures deal with n + i == 0 (after your first two patches fixing up arm and arm64, anyway).
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org
include/asm-generic/syscall.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/syscall.h b/include/asm-generic/syscall.h index 5b09392..49b35ab 100644 --- a/include/asm-generic/syscall.h +++ b/include/asm-generic/syscall.h @@ -106,7 +106,7 @@ void syscall_set_return_value(struct task_struct *task, struct pt_regs *regs,
- @task: task of interest, must be blocked
- @regs: task_pt_regs() of @task
- @i: argument index [0,5]
- @n: number of arguments; n+i must be [1,6].
- @n: number of arguments; n+i must be [0,6].
- @args: array filled with argument values
- Fetches @n arguments to the system call starting with the @i'th argument
@@ -126,7 +126,7 @@ void syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
- @task: task of interest, must be in system call entry tracing
- @regs: task_pt_regs() of @task
- @i: argument index [0,5]
- @n: number of arguments; n+i must be [1,6].
- @n: number of arguments; n+i must be [0,6].
- @args: array of argument values to store
- Changes @n arguments to the system call starting with the @i'th argument.
Acked-by: Will Deacon will.deacon@arm.com
Will
On Thu, Oct 03, 2013 at 06:47:43AM +0100, AKASHI Takahiro wrote:
# added Roland mcgrathr@chromium in CC for asm-generic/syscall.h
I modified my patch based on Will's comments. Speaking of arm, i + n is checked against SYSCALL_MAX_ARGS (== 7), but it seems that the kernel code assumes that the current max number of arguments would be 6. For example, SYSCALL_DEFINEn are defined from 0 to 6. Am i wrong?
We do have a 7 argument syscall on OABI ARM. See the original thread:
http://lists.infradead.org/pipermail/linux-arm-kernel/2012-February/085509.h...
Will
linaro-kernel@lists.linaro.org
-
AKASHI Takahiro -
Will Deacon