From 6789e01e9370b3b7f65d52138c5657eaa712b4d1 Mon Sep 17 00:00:00 2001 From: David Kalnischkies Date: Fri, 20 Nov 2015 00:54:07 +0100 Subject: do not segfault in cache generation on mmap failure MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Out of memory and similar circumstanzas could cause MMap::Map to fail and especially the mmap/malloc calls in it. With some additional checking we can avoid segfaults and similar in such situations – at least in theory as if this is a real out of memory everything we do to handle the error could just as well run into a memory problem as well… But at least in theory (if MMap::Map is made to fail always) we can deal with it so good that a user actually never sees a failure (as the cache it tries to load with it fails and is discarded, so that DynamicMMap takes over and a new one is build) instead of segfaulting. Closes: 803417 --- apt-pkg/contrib/mmap.cc | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'apt-pkg/contrib/mmap.cc') diff --git a/apt-pkg/contrib/mmap.cc b/apt-pkg/contrib/mmap.cc index 8e169027e..33c33d1c1 100644 --- a/apt-pkg/contrib/mmap.cc +++ b/apt-pkg/contrib/mmap.cc @@ -38,7 +38,7 @@ // --------------------------------------------------------------------- /* */ MMap::MMap(FileFd &F,unsigned long Flags) : Flags(Flags), iSize(0), - Base(0), SyncToFd(NULL) + Base(nullptr), SyncToFd(nullptr) { if ((Flags & NoImmMap) != NoImmMap) Map(F); @@ -48,7 +48,7 @@ MMap::MMap(FileFd &F,unsigned long Flags) : Flags(Flags), iSize(0), // --------------------------------------------------------------------- /* */ MMap::MMap(unsigned long Flags) : Flags(Flags), iSize(0), - Base(0), SyncToFd(NULL) + Base(nullptr), SyncToFd(nullptr) { } /*}}}*/ @@ -84,6 +84,8 @@ bool MMap::Map(FileFd &Fd) if ((Flags & ReadOnly) != ReadOnly) return _error->Error("Compressed file %s can only be mapped readonly", Fd.Name().c_str()); Base = malloc(iSize); + if (unlikely(Base == nullptr)) + return _error->Errno("MMap-compressed-malloc", _("Couldn't make mmap of %llu bytes"), iSize); SyncToFd = new FileFd(); if (Fd.Seek(0L) == false || Fd.Read(Base, iSize) == false) return _error->Error("Compressed file %s can't be read into mmap", Fd.Name().c_str()); @@ -92,7 +94,7 @@ bool MMap::Map(FileFd &Fd) // Map it. Base = (Flags & Fallback) ? MAP_FAILED : mmap(0,iSize,Prot,Map,Fd.Fd(),0); - if (Base == (void *)-1) + if (Base == MAP_FAILED) { if (errno == ENODEV || errno == EINVAL || (Flags & Fallback)) { @@ -102,6 +104,8 @@ bool MMap::Map(FileFd &Fd) { // for readonly, we don't need sync, so make it simple Base = malloc(iSize); + if (unlikely(Base == nullptr)) + return _error->Errno("MMap-malloc", _("Couldn't make mmap of %llu bytes"), iSize); SyncToFd = new FileFd(); return Fd.Read(Base, iSize); } @@ -111,13 +115,14 @@ bool MMap::Map(FileFd &Fd) return _error->Errno("mmap", _("Couldn't duplicate file descriptor %i"), Fd.Fd()); Base = calloc(iSize, 1); + if (unlikely(Base == nullptr)) + return _error->Errno("MMap-calloc", _("Couldn't make mmap of %llu bytes"), iSize); SyncToFd = new FileFd (dupped_fd); if (!SyncToFd->Seek(0L) || !SyncToFd->Read(Base, iSize)) return false; } else - return _error->Errno("mmap",_("Couldn't make mmap of %llu bytes"), - iSize); + return _error->Errno("MMap-mmap", _("Couldn't make mmap of %llu bytes"), iSize); } return true; -- cgit v1.2.3