| author |  LemonBoy <thatlemon@gmail.com> 2021-10-23 10:20:57+02:00 |
| committer |  Andrew Kelley <andrew@ziglang.org> 2021-10-23 22:48:25-04:00 |
| log | 1690b35770a97aec4b8a7b1b31a61b01e04f5656 |
| tree | 33e221f8173d3732e0cb5899dc5e50fe176ace78 |
| parent | 22b4c9e1a9595bd94ada4c500a430e2668ffcd07 |
std: Fix edge case in TLS tp calculation
The TLS area may be located in the upper part of the address space and,
if the platform expects a constant offset to be applied, may make the tp
register calculation overflow.
Use +% instead of +, the overflow is harmless.1 files changed, 4 insertions(+), 2 deletions(-)
lib- std
- os
- linux
lib/std/os/linux/tls.zig+4-2
| ... | ... | @@ -289,8 +289,10 @@ pub fn prepareTLS(area: []u8) usize { |
| 289 | 289 | // Copy the data |
| 290 | 290 | mem.copy(u8, area[tls_image.data_offset..], tls_image.init_data); |
| 291 | 291 | |
| 292 | // Return the corrected (if needed) value for the tp register | |
| 293 | return @ptrToInt(area.ptr) + tls_tp_offset + | |
| 292 | // Return the corrected value (if needed) for the tp register. | |
| 293 | // Overflow here is not a problem, the pointer arithmetic involving the tp | |
| 294 | // is done with wrapping semantics. | |
| 295 | return @ptrToInt(area.ptr) +% tls_tp_offset +% | |
| 294 | 296 | if (tls_tp_points_past_tcb) tls_image.data_offset else tls_image.tcb_offset; |
| 295 | 297 | } |
| 296 | 298 |