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authorDavid Howells <dhowells@redhat.com>2006-09-27 01:50:19 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-27 08:26:14 -0700
commitd00c7b993712e4bb16d0012b35b654e40159b327 (patch)
tree79f8fc60f8e41e054abc39b5d69e84d7a389777c /Documentation
parent7b4d5b8b39fd3701ed3693a89f2bd8f6ef49bce2 (diff)
[PATCH] NOMMU: Permit ptrace to ignore non-PROT_WRITE VMAs in NOMMU mode
Permit ptrace to modify a section that's non-shared but is marked unwritable, such as is obtained by mapping the text segment of an ELF-FDPIC executable binary with into a binary that's being ptraced[*]. [*] Under NOMMU conditions ptrace causes read-only MAP_PRIVATE mmaps to become totally private copies because if a private mapping was actually shared then the debugging setting breakpoints in it would potentially crash other processes. This is done by using the VM_MAYWRITE flag rather than the VM_WRITE flag when deciding whether to permit a write. Without this patch a debugger can't set breakpoints in the mapped text sections of executables that are mapped read-only private, even if the mmap() syscall has taken a private copy because PT_PTRACED is set. In addition, VM_MAYREAD is used instead of VM_READ for similar reasons. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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