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pstore: ram_core: fix incorrect success return when vmap() fails

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In persistent_ram_vmap(), vmap() may return NULL on failure.

If offset is non-zero, adding offset_in_page(start) causes the function
to return a non-NULL pointer even though the mapping failed.
persistent_ram_buffer_map() therefore incorrectly returns success.

Subsequent access to prz->buffer may dereference an invalid address
and cause crashes.

Add proper NULL checking for vmap() failures.

Signed-off-by: Ruipeng Qi <ruipengqi3@gmail.com>
Link: https://patch.msgid.link/20260203020358.3315299-1-ruipengqi3@gmail.com
Signed-off-by: Kees Cook <kees@kernel.org>
This commit is contained in:
Ruipeng Qi 2026-02-03 10:03:58 +08:00 committed by Kees Cook
parent 9448598b22
commit 05363abc76
1 changed files with 7 additions and 0 deletions
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7
fs/pstore/ram_core.c
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@ -446,6 +446,13 @@ static void *persistent_ram_vmap(phys_addr_t start, size_t size,
vaddr = vmap(pages, page_count, VM_MAP | VM_IOREMAP, prot); vaddr = vmap(pages, page_count, VM_MAP | VM_IOREMAP, prot);
kfree(pages); kfree(pages);
/*
* vmap() may fail and return NULL. Do not add the offset in this
* case, otherwise a NULL mapping would appear successful.
*/
if (!vaddr)
return NULL;
/* /*
* Since vmap() uses page granularity, we must add the offset * Since vmap() uses page granularity, we must add the offset
* into the page here, to get the byte granularity address * into the page here, to get the byte granularity address