In theory, some malloc calls with M_WAITOK can fail because the underlying Malloc() implementation in src/stand can fail. We should proactively detect this and fail in a helpful way, rather than waiting for the null pointer dereference.
Note to bug busters: this is an enhancement request that may languish (though hopefully not), please check with me before starting any timeout process on it. Thanks!
https://reviews.freebsd.org/D31106 has an experimental fix.
A commit in branch main references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=72821668b039c276914569e9caa1cdfa4e4cb674 commit 72821668b039c276914569e9caa1cdfa4e4cb674 Author: Warner Losh <imp@FreeBSD.org> AuthorDate: 2021-07-09 17:21:18 +0000 Commit: Warner Losh <imp@FreeBSD.org> CommitDate: 2021-07-09 17:21:18 +0000 stand/kmem_zalloc: panic when a M_WAITOK allocation fails Malloc() might return NULL, in which case we will panic with a NULL pointer deref. Make it panic when the allocation fails to preserve the postcondtion that we never return a non-NULL value. Reviewed by: tsoome PR: 249859 Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D31106 sys/sys/malloc.h | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)
A commit in branch stable/13 references this bug: URL: https://cgit.FreeBSD.org/src/commit/?id=9cd9a0c86924c350f83e5c8fbcadc84ee0d72e26 commit 9cd9a0c86924c350f83e5c8fbcadc84ee0d72e26 Author: Warner Losh <imp@FreeBSD.org> AuthorDate: 2021-07-09 17:21:18 +0000 Commit: Warner Losh <imp@FreeBSD.org> CommitDate: 2021-07-12 19:42:58 +0000 stand/kmem_zalloc: panic when a M_WAITOK allocation fails Malloc() might return NULL, in which case we will panic with a NULL pointer deref. Make it panic when the allocation fails to preserve the postcondtion that we never return a non-NULL value. Reviewed by: tsoome PR: 249859 Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D31106 (cherry picked from commit 72821668b039c276914569e9caa1cdfa4e4cb674) sys/sys/malloc.h | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)