From: Szabolcs Nagy <szabolcs.nagy@arm.com> To: Adhemerval Zanella <adhemerval.zanella@linaro.org> Cc: libc-alpha@sourceware.org, Mark Rutland <mark.rutland@arm.com>, kernel-hardening@lists.openwall.com, Catalin Marinas <catalin.marinas@arm.com>, linux-kernel@vger.kernel.org, Jeremy Linton <jeremy.linton@arm.com>, Mark Brown <broonie@kernel.org>, Topi Miettinen <toiwoton@gmail.com>, Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 3/6] elf: Fix failure handling in _dl_map_object_from_fd Date: Fri, 11 Dec 2020 09:32:56 +0000 [thread overview] Message-ID: <20201211093255.GD24625@arm.com> (raw) In-Reply-To: <1525639f-560f-2677-b1cb-f904b3552c71@linaro.org> The 12/10/2020 15:25, Adhemerval Zanella wrote: > On 27/11/2020 10:20, Szabolcs Nagy via Libc-alpha wrote: > > There are many failure paths that call lose to do local cleanups > > in _dl_map_object_from_fd, but it did not clean everything. > > > > Handle l_phdr, l_libname and mapped segments in the common failure > > handling code. > > > > There are various bits that may not be cleaned properly on failure > > (e.g. executable stack, tlsid, incomplete dl_map_segments). > > --- > > elf/dl-load.c | 24 +++++++++++++++--------- > > 1 file changed, 15 insertions(+), 9 deletions(-) > > > > diff --git a/elf/dl-load.c b/elf/dl-load.c > > index 21e55deb19..9c71b7562c 100644 > > --- a/elf/dl-load.c > > +++ b/elf/dl-load.c > > @@ -914,8 +914,15 @@ lose (int code, int fd, const char *name, char *realname, struct link_map *l, > > /* The file might already be closed. */ > > if (fd != -1) > > (void) __close_nocancel (fd); > > + if (l != NULL && l->l_map_start != 0) > > + _dl_unmap_segments (l); > > if (l != NULL && l->l_origin != (char *) -1l) > > free ((char *) l->l_origin); > > + if (l != NULL && !l->l_libname->dont_free) > > + free (l->l_libname); > > + if (l != NULL && l->l_phdr_allocated) > > + free ((void *) l->l_phdr); > > + > > free (l); > > free (realname); > > > > @@ -1256,7 +1263,11 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, > > errstring = _dl_map_segments (l, fd, header, type, loadcmds, nloadcmds, > > maplength, has_holes, loader); > > if (__glibc_unlikely (errstring != NULL)) > > - goto call_lose; > > + { > > + /* Mappings can be in an inconsistent state: avoid unmap. */ > > + l->l_map_start = l->l_map_end = 0; > > + goto call_lose; > > + } > > > > /* Process program headers again after load segments are mapped in > > case processing requires accessing those segments. Scan program > > In this case I am failing to see who would be responsible to unmap > l_map_start int the type == ET_DYN where first mmap succeeds but > with a later mmap failure in any load command. failures are either cleaned up locally in this function via lose or after a clean return via dlclose. failures that are not cleaned up will leak resources. _dl_map_segments failure is not cleaned up (the mappings are in an unknown state). however after a successful _dl_map_segments later failures can clean the mappings and that's what i fixed here. i did not try to fix transitive design bugs (such as leaks in _dl_map_segments) that would require interface change or local cleanups in those other functions. > > @@ -1294,14 +1305,6 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, > > || (__glibc_unlikely (l->l_flags_1 & DF_1_PIE) > > && __glibc_unlikely ((mode & __RTLD_OPENEXEC) == 0))) > > { > > - /* We are not supposed to load this object. Free all resources. */ > > - _dl_unmap_segments (l); > > - > > - if (!l->l_libname->dont_free) > > - free (l->l_libname); > > - > > - if (l->l_phdr_allocated) > > - free ((void *) l->l_phdr); > > > > if (l->l_flags_1 & DF_1_PIE) > > errstring > > @@ -1392,6 +1395,9 @@ cannot enable executable stack as shared object requires"); > > /* Signal that we closed the file. */ > > fd = -1; > > > > + /* Failures before this point are handled locally via lose. > > + No more failures are allowed in this function until return. */ > > + > > /* If this is ET_EXEC, we should have loaded it as lt_executable. */ > > assert (type != ET_EXEC || l->l_type == lt_executable); > > > > > > Ok.
WARNING: multiple messages have this Message-ID (diff)
From: Szabolcs Nagy <szabolcs.nagy@arm.com> To: Adhemerval Zanella <adhemerval.zanella@linaro.org> Cc: Mark Rutland <mark.rutland@arm.com>, libc-alpha@sourceware.org, kernel-hardening@lists.openwall.com, Catalin Marinas <catalin.marinas@arm.com>, linux-kernel@vger.kernel.org, Jeremy Linton <jeremy.linton@arm.com>, Mark Brown <broonie@kernel.org>, Topi Miettinen <toiwoton@gmail.com>, Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 3/6] elf: Fix failure handling in _dl_map_object_from_fd Date: Fri, 11 Dec 2020 09:32:56 +0000 [thread overview] Message-ID: <20201211093255.GD24625@arm.com> (raw) In-Reply-To: <1525639f-560f-2677-b1cb-f904b3552c71@linaro.org> The 12/10/2020 15:25, Adhemerval Zanella wrote: > On 27/11/2020 10:20, Szabolcs Nagy via Libc-alpha wrote: > > There are many failure paths that call lose to do local cleanups > > in _dl_map_object_from_fd, but it did not clean everything. > > > > Handle l_phdr, l_libname and mapped segments in the common failure > > handling code. > > > > There are various bits that may not be cleaned properly on failure > > (e.g. executable stack, tlsid, incomplete dl_map_segments). > > --- > > elf/dl-load.c | 24 +++++++++++++++--------- > > 1 file changed, 15 insertions(+), 9 deletions(-) > > > > diff --git a/elf/dl-load.c b/elf/dl-load.c > > index 21e55deb19..9c71b7562c 100644 > > --- a/elf/dl-load.c > > +++ b/elf/dl-load.c > > @@ -914,8 +914,15 @@ lose (int code, int fd, const char *name, char *realname, struct link_map *l, > > /* The file might already be closed. */ > > if (fd != -1) > > (void) __close_nocancel (fd); > > + if (l != NULL && l->l_map_start != 0) > > + _dl_unmap_segments (l); > > if (l != NULL && l->l_origin != (char *) -1l) > > free ((char *) l->l_origin); > > + if (l != NULL && !l->l_libname->dont_free) > > + free (l->l_libname); > > + if (l != NULL && l->l_phdr_allocated) > > + free ((void *) l->l_phdr); > > + > > free (l); > > free (realname); > > > > @@ -1256,7 +1263,11 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, > > errstring = _dl_map_segments (l, fd, header, type, loadcmds, nloadcmds, > > maplength, has_holes, loader); > > if (__glibc_unlikely (errstring != NULL)) > > - goto call_lose; > > + { > > + /* Mappings can be in an inconsistent state: avoid unmap. */ > > + l->l_map_start = l->l_map_end = 0; > > + goto call_lose; > > + } > > > > /* Process program headers again after load segments are mapped in > > case processing requires accessing those segments. Scan program > > In this case I am failing to see who would be responsible to unmap > l_map_start int the type == ET_DYN where first mmap succeeds but > with a later mmap failure in any load command. failures are either cleaned up locally in this function via lose or after a clean return via dlclose. failures that are not cleaned up will leak resources. _dl_map_segments failure is not cleaned up (the mappings are in an unknown state). however after a successful _dl_map_segments later failures can clean the mappings and that's what i fixed here. i did not try to fix transitive design bugs (such as leaks in _dl_map_segments) that would require interface change or local cleanups in those other functions. > > @@ -1294,14 +1305,6 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd, > > || (__glibc_unlikely (l->l_flags_1 & DF_1_PIE) > > && __glibc_unlikely ((mode & __RTLD_OPENEXEC) == 0))) > > { > > - /* We are not supposed to load this object. Free all resources. */ > > - _dl_unmap_segments (l); > > - > > - if (!l->l_libname->dont_free) > > - free (l->l_libname); > > - > > - if (l->l_phdr_allocated) > > - free ((void *) l->l_phdr); > > > > if (l->l_flags_1 & DF_1_PIE) > > errstring > > @@ -1392,6 +1395,9 @@ cannot enable executable stack as shared object requires"); > > /* Signal that we closed the file. */ > > fd = -1; > > > > + /* Failures before this point are handled locally via lose. > > + No more failures are allowed in this function until return. */ > > + > > /* If this is ET_EXEC, we should have loaded it as lt_executable. */ > > assert (type != ET_EXEC || l->l_type == lt_executable); > > > > > > Ok. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-12-11 9:35 UTC|newest] Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-11-27 13:19 [PATCH v2 0/6] aarch64: avoid mprotect(PROT_BTI|PROT_EXEC) [BZ #26831] Szabolcs Nagy 2020-11-27 13:19 ` Szabolcs Nagy 2020-11-27 13:19 ` [PATCH v2 1/6] aarch64: Fix missing BTI protection from dependencies [BZ #26926] Szabolcs Nagy 2020-11-27 13:19 ` Szabolcs Nagy 2020-12-10 17:51 ` Adhemerval Zanella 2020-12-10 17:51 ` Adhemerval Zanella 2020-12-11 15:33 ` Szabolcs Nagy 2020-12-11 15:33 ` Szabolcs Nagy 2020-11-27 13:20 ` [PATCH v2 2/6] elf: lose is closely tied to _dl_map_object_from_fd Szabolcs Nagy 2020-11-27 13:20 ` Szabolcs Nagy 2020-11-27 13:20 ` [PATCH v2 3/6] elf: Fix failure handling in _dl_map_object_from_fd Szabolcs Nagy 2020-11-27 13:20 ` Szabolcs Nagy 2020-12-10 18:25 ` Adhemerval Zanella 2020-12-10 18:25 ` Adhemerval Zanella 2020-12-11 9:32 ` Szabolcs Nagy [this message] 2020-12-11 9:32 ` Szabolcs Nagy 2020-11-27 13:20 ` [PATCH v2 4/6] elf: Move note processing after l_phdr is updated Szabolcs Nagy 2020-11-27 13:20 ` Szabolcs Nagy 2020-11-27 13:21 ` [PATCH v2 5/6] elf: Pass the fd to note processing Szabolcs Nagy 2020-11-27 13:21 ` Szabolcs Nagy 2020-12-10 18:35 ` Adhemerval Zanella 2020-12-10 18:35 ` Adhemerval Zanella 2020-11-27 13:21 ` [PATCH v2 6/6] aarch64: Use mmap to add PROT_BTI instead of mprotect [BZ #26831] Szabolcs Nagy 2020-11-27 13:21 ` Szabolcs Nagy 2020-12-02 8:55 ` [PATCH v3 1/2] aarch64: align address for BTI protection [BZ #26988] Szabolcs Nagy 2020-12-02 8:55 ` Szabolcs Nagy 2020-12-10 18:49 ` Adhemerval Zanella 2020-12-10 18:49 ` Adhemerval Zanella 2020-12-02 8:55 ` [PATCH v3 2/2] aarch64: Use mmap to add PROT_BTI instead of mprotect [BZ #26831] Szabolcs Nagy 2020-12-02 8:55 ` Szabolcs Nagy 2020-12-10 19:12 ` Adhemerval Zanella 2020-12-10 19:12 ` Adhemerval Zanella 2020-11-30 15:56 ` [PATCH v2 0/6] aarch64: avoid mprotect(PROT_BTI|PROT_EXEC) " Szabolcs Nagy 2020-11-30 15:56 ` Szabolcs Nagy 2020-12-03 17:30 ` Catalin Marinas 2020-12-03 17:30 ` Catalin Marinas 2020-12-07 20:03 ` Szabolcs Nagy 2020-12-07 20:03 ` Szabolcs Nagy 2020-12-11 17:46 ` Catalin Marinas 2020-12-11 17:46 ` Catalin Marinas
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