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a=ed25519-sha256; t=1774346430; l=1805; i=shivamkalra98@zohomail.in; s=20260212; h=from:subject:message-id; bh=LSUYWjYOjJYKYliRO3bYLhKxcMuMIBGaVN2tymO6+ew=; b=rnj4cYZkzkJ86bsOX6qnSlWl5dROAsN7ly5d6iDcEQPVC7kXfPVNp2+aT/Y+JklM8mQ3ukx5Y aizhMbSd8BvDTD8JdpVEUyF3RLaOHctT575Mvr0Wj0aLjsC/fSjn72S X-Developer-Key: i=shivamkalra98@zohomail.in; a=ed25519; pk=9Q+S1LD/xjbjL7bEaLIlwRADBwU/6LJq7lYm8LFrkQE= X-Endpoint-Received: by B4 Relay for shivamkalra98@zohomail.in/20260212 with auth_id=633 X-Original-From: Shivam Kalra Reply-To: shivamkalra98@zohomail.in X-Rspamd-Queue-Id: 4475A1C0008 X-Stat-Signature: ef4659sbxepfu4qocmo75ubz8653adxb X-Rspam-User: X-Rspamd-Server: rspam07 X-HE-Tag: 1774346434-120297 X-HE-Meta: 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 FTDuJa/j idocvZNdWtF056zm0fm1SpaoXeRAJ4KJchlhubbPfG1iJpFG+ULR1Chhi7RwVqe3rpHg7Kkl/Qt+06oZvwv0s/31PfjsY7K9SmVgVLrwwciQLYdT7PJ8lABZBi7WmwXtisMF0xz/yQIonXIyeiHOOwzOGHFo7l/BMHYXjo1UHBgD4jGiE+BJ+/D4tYbT5j+to0BBIN3B73/tDdk//vTAuwdAv6PddtZmGGbqzG273dYgP1a1W+gRlGJCE8i1AWElB9tNintcVkQe84F2uN+muc871JX7J0eqTMatacb/ZgVndCtJuqtEssaQBHo/hO2ivwrQNiL0v7Gbm2n9M6buztoHHF33vKDMjAhHM8bd6N4X1iac= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Shivam Kalra When growing an existing vmalloc allocation in-place, zero the newly exposed memory region [old_size, size) if the caller requested it via __GFP_ZERO (checked via want_init_on_alloc(flags)). Previously, the code assumed that the unused capacity in the vm_struct was already zeroed either at initial allocation time or during a prior shrink. However, if an intermediate shrink operation occurred without __GFP_ZERO and without init_on_free enabled, the "freed" portion of the allocation would retain its old data. If a subsequent grow-in-place operation then explicitly requests __GFP_ZERO, failing to zero the memory here would violate the allocation flags and leak the previously discarded, potentially sensitive data. Signed-off-by: Shivam Kalra --- mm/vmalloc.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 133c3b0418fe..ddb689bf9ba5 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4368,13 +4368,16 @@ void *vrealloc_node_align_noprof(const void *p, size_t size, unsigned long align * We already have the bytes available in the allocation; use them. */ if (size <= (size_t)vm->nr_pages << PAGE_SHIFT) { - /* - * No need to zero memory here, as unused memory will have - * already been zeroed at initial allocation time or during - * realloc shrink time. - */ vm->requested_size = size; kasan_vrealloc(p, old_size, size); + + /* + * Zero the newly exposed bytes if requested. + * The region [old_size, size) may contain stale data from + * a previous shrink that did not use __GFP_ZERO. + */ + if (want_init_on_alloc(flags)) + memset((void *)p + old_size, 0, size - old_size); return (void *)p; } -- 2.43.0