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vec: with_capacity: check for overflow #10417

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Nov 11, 2013
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vec: with_capacity: check for overflow #10417

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6 changes: 5 additions & 1 deletion src/libstd/vec.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -186,7 +186,11 @@ pub fn with_capacity<T>(capacity: uint) -> ~[T] {
vec
} else {
let alloc = capacity * mem::nonzero_size_of::<T>();
let ptr = malloc_raw(alloc + mem::size_of::<Vec<()>>()) as *mut Vec<()>;
let size = alloc + mem::size_of::<Vec<()>>();
if alloc / mem::nonzero_size_of::<T>() != capacity || size < alloc {
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Isn't this check incorrect, because the header is included in alloc?

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No. The header comes from size_of::<Vec<()>>. This is the same code used
for overflow handling elsewhere. cc @thestinger

On Mon, Nov 11, 2013 at 6:23 AM, Huon Wilson notifications@gh.neting.ccwrote:

In src/libstd/vec.rs:

@@ -186,7 +186,11 @@ pub fn with_capacity(capacity: uint) -> ~[T] {
vec
} else {
let alloc = capacity * mem::nonzero_size_of::();

  •        let ptr = malloc_raw(alloc + mem::size_of::<Vec<()>>()) as *mut Vec<()>;

  •        let size = alloc + mem::size_of::<Vec<()>>();

  •        if alloc / mem::nonzero_size_of::<T>() != capacity || size < alloc {

Isn't this check incorrect, because the header is included in alloc?

—
Reply to this email directly or view it on GitHubhttps://github.com//pull/10417/files#r7556668
.

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Oh, of course... it's alloc / ... not size / ....

fail!("vector size is too large: {}", capacity);
}
let ptr = malloc_raw(size) as *mut Vec<()>;
(*ptr).alloc = alloc;
(*ptr).fill = 0;
cast::transmute(ptr)
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