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Fix in_exposed_bounds security vulnerability #1114

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merged 1 commit into from
Jul 16, 2018
Merged

Fix in_exposed_bounds security vulnerability #1114

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15 changes: 13 additions & 2 deletions kernel/src/process.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -450,6 +450,10 @@ impl Process<'a> {
unsafe { self.memory.as_ptr().offset(self.memory.len() as isize) }
}

fn mem_break(&self) -> *const u8 {
self.kernel_memory_break.get()
}

crate fn flash_start(&self) -> *const u8 {
self.flash.as_ptr()
}
Expand Down Expand Up @@ -790,10 +794,17 @@ impl Process<'a> {
}
}

/// Checks if the buffer represented by the passed in base pointer and size
/// are within the memory bounds currently exposed to the processes (i.e.
/// ending at `kernel_memory_break`. If this method returns true, the buffer
/// is guaranteed to be accessible to the process and to not overlap with
/// the grant region.
crate fn in_exposed_bounds(&self, buf_start_addr: *const u8, size: usize) -> bool {
let buf_end_addr = unsafe { buf_start_addr.offset(size as isize) };
let buf_end_addr = buf_start_addr.wrapping_offset(size as isize);

buf_start_addr >= self.mem_start() && buf_end_addr <= self.mem_end()
buf_end_addr >= buf_start_addr
&& buf_start_addr >= self.mem_start()
&& buf_end_addr <= self.mem_break()
}

crate unsafe fn alloc(&self, size: usize) -> Option<&mut [u8]> {
Expand Down