From: Linus Torvalds Date: Wed, 8 Apr 2026 20:18:57 +0000 (-0700) Subject: x86: shadow stacks: proper error handling for mmap lock X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=52f657e34d7b21b47434d9d8b26fa7f6778b63a0;p=thirdparty%2Fkernel%2Flinux.git x86: shadow stacks: proper error handling for mmap lock 김영민 reports that shstk_pop_sigframe() doesn't check for errors from mmap_read_lock_killable(), which is a silly oversight, and also shows that we haven't marked those functions with "__must_check", which would have immediately caught it. So let's fix both issues. Reported-by: 김영민 Acked-by: Oleg Nesterov Acked-by: Dave Hansen Acked-by: Rick Edgecombe Signed-off-by: Linus Torvalds --- diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c index 978232b6d48d..ff8edea8511b 100644 --- a/arch/x86/kernel/shstk.c +++ b/arch/x86/kernel/shstk.c @@ -351,7 +351,8 @@ static int shstk_pop_sigframe(unsigned long *ssp) need_to_check_vma = PAGE_ALIGN(*ssp) == *ssp; if (need_to_check_vma) - mmap_read_lock_killable(current->mm); + if (mmap_read_lock_killable(current->mm)) + return -EINTR; err = get_shstk_data(&token_addr, (unsigned long __user *)*ssp); if (unlikely(err)) diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h index 93eca48bc443..04b8f61ece5d 100644 --- a/include/linux/mmap_lock.h +++ b/include/linux/mmap_lock.h @@ -546,7 +546,7 @@ static inline void mmap_write_lock_nested(struct mm_struct *mm, int subclass) __mmap_lock_trace_acquire_returned(mm, true, true); } -static inline int mmap_write_lock_killable(struct mm_struct *mm) +static inline int __must_check mmap_write_lock_killable(struct mm_struct *mm) { int ret; @@ -593,7 +593,7 @@ static inline void mmap_read_lock(struct mm_struct *mm) __mmap_lock_trace_acquire_returned(mm, false, true); } -static inline int mmap_read_lock_killable(struct mm_struct *mm) +static inline int __must_check mmap_read_lock_killable(struct mm_struct *mm) { int ret; @@ -603,7 +603,7 @@ static inline int mmap_read_lock_killable(struct mm_struct *mm) return ret; } -static inline bool mmap_read_trylock(struct mm_struct *mm) +static inline bool __must_check mmap_read_trylock(struct mm_struct *mm) { bool ret;