Currently the rseq constructor, rseq_init(), assumes that glibc always has the support for rseq symbols (__rseq_size for instance). However, glibc supports rseq from version 2.35 onwards. As a result, for the systems that run glibc less than 2.35, the global rseq_size remains initialized to -1U. When a thread then tries to register for rseq, get_rseq_min_alloc_size() would end up returning -1U, which is incorrect. Hence, initialize rseq_size for the cases where glibc doesn't have the support for rseq symbols.
Cc: stable@vger.kernel.org Fixes: 73a4f5a704a2 ("selftests/rseq: Fix mm_cid test failure") Signed-off-by: Raghavendra Rao Ananta rananta@google.com --- tools/testing/selftests/rseq/rseq.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c index 5b9772cdf265..9eb5356f25fa 100644 --- a/tools/testing/selftests/rseq/rseq.c +++ b/tools/testing/selftests/rseq/rseq.c @@ -142,6 +142,16 @@ unsigned int get_rseq_kernel_feature_size(void) return ORIG_RSEQ_FEATURE_SIZE; }
+static void set_default_rseq_size(void) +{ + unsigned int rseq_kernel_feature_size = get_rseq_kernel_feature_size(); + + if (rseq_kernel_feature_size < ORIG_RSEQ_ALLOC_SIZE) + rseq_size = rseq_kernel_feature_size; + else + rseq_size = ORIG_RSEQ_ALLOC_SIZE; +} + int rseq_register_current_thread(void) { int rc; @@ -219,12 +229,7 @@ void rseq_init(void) fallthrough; case ORIG_RSEQ_ALLOC_SIZE: { - unsigned int rseq_kernel_feature_size = get_rseq_kernel_feature_size(); - - if (rseq_kernel_feature_size < ORIG_RSEQ_ALLOC_SIZE) - rseq_size = rseq_kernel_feature_size; - else - rseq_size = ORIG_RSEQ_ALLOC_SIZE; + set_default_rseq_size(); break; } default: @@ -239,8 +244,10 @@ void rseq_init(void) rseq_size = 0; return; } + rseq_offset = (void *)&__rseq_abi - rseq_thread_pointer(); rseq_flags = 0; + set_default_rseq_size(); }
static __attribute__((destructor))
base-commit: 40384c840ea1944d7c5a392e8975ed088ecf0b37
On 12/10/24 15:44, Raghavendra Rao Ananta wrote:
Currently the rseq constructor, rseq_init(), assumes that glibc always has the support for rseq symbols (__rseq_size for instance). However, glibc supports rseq from version 2.35 onwards. As a result, for the systems that run glibc less than 2.35, the global rseq_size remains initialized to -1U. When a thread then tries to register for rseq, get_rseq_min_alloc_size() would end up returning -1U, which is incorrect. Hence, initialize rseq_size for the cases where glibc doesn't have the support for rseq symbols.
Cc: stable@vger.kernel.org Fixes: 73a4f5a704a2 ("selftests/rseq: Fix mm_cid test failure") Signed-off-by: Raghavendra Rao Ananta rananta@google.com
Applied to linux_kselftest next for Linux 6.14-rc1 after fixing the commit if for Fixes tag
thanks, -- Shuah
On 2025-01-13 18:06, Shuah Khan wrote:
On 12/10/24 15:44, Raghavendra Rao Ananta wrote:
Currently the rseq constructor, rseq_init(), assumes that glibc always has the support for rseq symbols (__rseq_size for instance). However, glibc supports rseq from version 2.35 onwards. As a result, for the systems that run glibc less than 2.35, the global rseq_size remains initialized to -1U. When a thread then tries to register for rseq, get_rseq_min_alloc_size() would end up returning -1U, which is incorrect. Hence, initialize rseq_size for the cases where glibc doesn't have the support for rseq symbols.
Cc: stable@vger.kernel.org Fixes: 73a4f5a704a2 ("selftests/rseq: Fix mm_cid test failure") Signed-off-by: Raghavendra Rao Ananta rananta@google.com
Applied to linux_kselftest next for Linux 6.14-rc1 after fixing the commit if for Fixes tag
Hi Shuah,
I did not review nor ack this patch. I need to review it carefully to make sure it does not break anything else moving forward.
Please wait before merging.
Thanks,
Mathieu
thanks, -- Shuah
On 2025-01-14 09:07, Mathieu Desnoyers wrote:
On 2025-01-13 18:06, Shuah Khan wrote:
On 12/10/24 15:44, Raghavendra Rao Ananta wrote:
Currently the rseq constructor, rseq_init(), assumes that glibc always has the support for rseq symbols (__rseq_size for instance). However, glibc supports rseq from version 2.35 onwards. As a result, for the systems that run glibc less than 2.35, the global rseq_size remains initialized to -1U. When a thread then tries to register for rseq, get_rseq_min_alloc_size() would end up returning -1U, which is incorrect. Hence, initialize rseq_size for the cases where glibc doesn't have the support for rseq symbols.
Cc: stable@vger.kernel.org Fixes: 73a4f5a704a2 ("selftests/rseq: Fix mm_cid test failure") Signed-off-by: Raghavendra Rao Ananta rananta@google.com
Applied to linux_kselftest next for Linux 6.14-rc1 after fixing the commit if for Fixes tag
Hi Shuah,
I did not review nor ack this patch. I need to review it carefully to make sure it does not break anything else moving forward.
Please wait before merging.
I am preparing an alternative fix which keeps the selftests code in sync with librseq.
Thanks,
Mathieu
Thanks,
Mathieu
thanks, -- Shuah
On 1/14/25 07:27, Mathieu Desnoyers wrote:
On 2025-01-14 09:07, Mathieu Desnoyers wrote:
On 2025-01-13 18:06, Shuah Khan wrote:
On 12/10/24 15:44, Raghavendra Rao Ananta wrote:
Currently the rseq constructor, rseq_init(), assumes that glibc always has the support for rseq symbols (__rseq_size for instance). However, glibc supports rseq from version 2.35 onwards. As a result, for the systems that run glibc less than 2.35, the global rseq_size remains initialized to -1U. When a thread then tries to register for rseq, get_rseq_min_alloc_size() would end up returning -1U, which is incorrect. Hence, initialize rseq_size for the cases where glibc doesn't have the support for rseq symbols.
Cc: stable@vger.kernel.org Fixes: 73a4f5a704a2 ("selftests/rseq: Fix mm_cid test failure") Signed-off-by: Raghavendra Rao Ananta rananta@google.com
Applied to linux_kselftest next for Linux 6.14-rc1 after fixing the commit if for Fixes tag
Hi Shuah,
I did not review nor ack this patch. I need to review it carefully to make sure it does not break anything else moving forward.
Please wait before merging.
I am preparing an alternative fix which keeps the selftests code in sync with librseq.
Sorry for the mixup. I will go drop this now.
thanks, -- Shuah
linux-stable-mirror@lists.linaro.org
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Mathieu Desnoyers -
Raghavendra Rao Ananta -
Shuah Khan