git: 7ef5c19b219e - main - kern linker: Don't invoke dtors without having invoked ctors
- Go to: [ bottom of page ] [ top of archives ] [ this month ]
Date: Sun, 31 Mar 2024 18:15:53 UTC
The branch main has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=7ef5c19b219e47684afd9d8d9126df39edc8d885 commit 7ef5c19b219e47684afd9d8d9126df39edc8d885 Author: Mark Johnston <markj@FreeBSD.org> AuthorDate: 2024-03-31 18:14:02 +0000 Commit: Mark Johnston <markj@FreeBSD.org> CommitDate: 2024-03-31 18:15:11 +0000 kern linker: Don't invoke dtors without having invoked ctors I have a kernel module which fails to load because of an unrecognized relocation type. link_elf_load_file() fails before the module's ctors are invoked and it calls linker_file_unload(), which causes the module's dtors to be executed, resulting in a kernel panic. Add a flag to the linker file to ensure that dtors are not invoked if unloading due to an error prior to ctors being invoked. At the moment I only implemented this for link_elf_obj.c since link_elf.c doesn't invoke dtors, but I refactored link_elf.c to make them more similar. Fixes: 9e575fadf491 ("link_elf_obj: Invoke fini callbacks") Reviewed by: zlei, kib MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D44559 --- sys/kern/kern_linker.c | 1 + sys/kern/link_elf.c | 15 +++++++++++++-- sys/kern/link_elf_obj.c | 30 +++++++++++++++++++++++++++--- sys/sys/linker.h | 5 +++++ 4 files changed, 46 insertions(+), 5 deletions(-) diff --git a/sys/kern/kern_linker.c b/sys/kern/kern_linker.c index 54b7466124db..08b85867d781 100644 --- a/sys/kern/kern_linker.c +++ b/sys/kern/kern_linker.c @@ -657,6 +657,7 @@ linker_make_file(const char *pathname, linker_class_t lc) return (NULL); lf->ctors_addr = 0; lf->ctors_size = 0; + lf->ctors_invoked = LF_NONE; lf->dtors_addr = 0; lf->dtors_size = 0; lf->refs = 1; diff --git a/sys/kern/link_elf.c b/sys/kern/link_elf.c index b08c19f3c018..9f9c10456b60 100644 --- a/sys/kern/link_elf.c +++ b/sys/kern/link_elf.c @@ -358,7 +358,7 @@ link_elf_error(const char *filename, const char *s) } static void -link_elf_invoke_ctors(caddr_t addr, size_t size) +link_elf_invoke_cbs(caddr_t addr, size_t size) { void (**ctor)(void); size_t i, cnt; @@ -373,6 +373,17 @@ link_elf_invoke_ctors(caddr_t addr, size_t size) } } +static void +link_elf_invoke_ctors(linker_file_t lf) +{ + KASSERT(lf->ctors_invoked == LF_NONE, + ("%s: file %s ctor state %d", + __func__, lf->filename, lf->ctors_invoked)); + + link_elf_invoke_cbs(lf->ctors_addr, lf->ctors_size); + lf->ctors_invoked = LF_CTORS; +} + /* * Actions performed after linking/loading both the preloaded kernel and any * modules; whether preloaded or dynamicly loaded. @@ -403,7 +414,7 @@ link_elf_link_common_finish(linker_file_t lf) #endif /* Invoke .ctors */ - link_elf_invoke_ctors(lf->ctors_addr, lf->ctors_size); + link_elf_invoke_ctors(lf); return (0); } diff --git a/sys/kern/link_elf_obj.c b/sys/kern/link_elf_obj.c index c8ccebea0832..a7c7d4826322 100644 --- a/sys/kern/link_elf_obj.c +++ b/sys/kern/link_elf_obj.c @@ -658,6 +658,30 @@ link_elf_invoke_cbs(caddr_t addr, size_t size) } } +static void +link_elf_invoke_ctors(linker_file_t lf) +{ + KASSERT(lf->ctors_invoked == LF_NONE, + ("%s: file %s ctor state %d", + __func__, lf->filename, lf->ctors_invoked)); + + link_elf_invoke_cbs(lf->ctors_addr, lf->ctors_size); + lf->ctors_invoked = LF_CTORS; +} + +static void +link_elf_invoke_dtors(linker_file_t lf) +{ + KASSERT(lf->ctors_invoked != LF_DTORS, + ("%s: file %s ctor state %d", + __func__, lf->filename, lf->ctors_invoked)); + + if (lf->ctors_invoked == LF_CTORS) { + link_elf_invoke_cbs(lf->dtors_addr, lf->dtors_size); + lf->ctors_invoked = LF_DTORS; + } +} + static int link_elf_link_preload_finish(linker_file_t lf) { @@ -684,7 +708,7 @@ link_elf_link_preload_finish(linker_file_t lf) /* Apply protections now that relocation processing is complete. */ link_elf_protect(ef); - link_elf_invoke_cbs(lf->ctors_addr, lf->ctors_size); + link_elf_invoke_ctors(lf); return (0); } @@ -1239,7 +1263,7 @@ link_elf_load_file(linker_class_t cls, const char *filename, #endif link_elf_protect(ef); - link_elf_invoke_cbs(lf->ctors_addr, lf->ctors_size); + link_elf_invoke_ctors(lf); *result = lf; out: @@ -1259,7 +1283,7 @@ link_elf_unload_file(linker_file_t file) elf_file_t ef = (elf_file_t) file; u_int i; - link_elf_invoke_cbs(file->dtors_addr, file->dtors_size); + link_elf_invoke_dtors(file); /* Notify MD code that a module is being unloaded. */ elf_cpu_unload_file(file); diff --git a/sys/sys/linker.h b/sys/sys/linker.h index b6184f4fc876..52fbeb5584ff 100644 --- a/sys/sys/linker.h +++ b/sys/sys/linker.h @@ -82,6 +82,11 @@ struct linker_file { size_t size; /* size of file */ caddr_t ctors_addr; /* address of .ctors/.init_array */ size_t ctors_size; /* size of .ctors/.init_array */ + enum { + LF_NONE = 0, + LF_CTORS, + LF_DTORS, + } ctors_invoked; /* have we run ctors yet? */ caddr_t dtors_addr; /* address of .dtors/.fini_array */ size_t dtors_size; /* size of .dtors/.fini_array */ int ndeps; /* number of dependencies */